Every holy city has a founding myth.
Istanbul's story begins with the legend
of a sea voyage by a Greek King named Byzas,
son of the sea god Poseidon,
who was said to have arrived here for the first time
over two and half thousand years ago.
King Byzas went to see the Delphic Oracle
and the Oracle told him, "You will build a great city opposite the blind."
He was bewildered and mystified by this Delphic utterance.
But anyway, he set sail
and he only understood its meaning
when he sailed right down here into the Golden Horn,
for on one side he saw a Greek settlement
and on the other side he saw the perfect strategic position
for a great city but with no city built there.
He understood immediately that they must have been blind
to build it in the wrong place.
He went to the right place and he started to build.
Byzas gave his name to the city he founded
and the empire it ultimately became - Byzantium.
Here a metropolis was built which would itself become a legend -
the bridge of continents, the battleground of faiths.
And along with Jerusalem and Rome,
one of the greatest holy cities in the world.
For 26 centuries this is the view that you saw
when you arrived at this famous city.
This is how you caught your first glimpse of its palaces,
its churches, its temples.
Conquerors and pilgrims,
traders and travellers came here for its power,
its holiness and its pleasure.
No wonder they called it the city of the world's desire.
Today, Istanbul's skyline is defined
by the minarets of the Muslims who've made this city their own.
MUEZZIN CALLING
The air is filled with the calls to prayer
for a mainly Islamic population.
But this is only the latest manifestation
of this multi-dimensional, ever-changing city.
Before them, the temples and churches of Greek, Roman and Christian gods
dominated these streets.
It was in Constantinople
that the Virgin Mary was said to have defended the city on the ramparts.
It was here that the Muslim armies burst into the Christian city.
These are the streets that have been the battleground
for some of the fiercest political and religious conflicts
of the last two millennia.
Istanbul has been the focus of passion
for the believers of two world religions.
And I've come here with the questions of both historian and traveller -
to examine the fabric of a place
which has been the sacred imperial capital of two empires -
one Islamic, one Christian -
and yet started out as little more than a humble fishing village.
In this series, I want to find out just how Byzantium became
the very definition of heaven-blessed legitimacy,
when it began with no claims at all to divine favour.
Since its founding,
Istanbul has been a city with many different identities.
And with each one has come a different name.
First it was called Byzantium
and then it was renamed Constantinople,
after the Roman Emperor, Constantine the Great.
And now it's Turkish, it's Istanbul.
But whatever you call it,
it's still the same utterly extraordinary place.
And if you walk around Istanbul today,
it's this most recent phase of the city's history
that takes centre stage - its mosques, its minarets.
But if you look a little more closely,
sometimes in rather surprising places,
you can begin to glimpse this city's forgotten past.
All over Istanbul, its earliest history lies in ruins.
Every now and then, a broken pillar or a crumbling wall
will give a hint of a lost world.
Many of the earliest remains date back to the 4th century AD,
when it was a Roman city.
But to get a glimpse of the people who first lived here,
you have to get below the surface - quite literally.
Under one of Istanbul's busiest streets,
is one of its greatest treasures -
a cavernous underworld known as the Basilica Cistern,
a place which gives us a fascinating insight into this city's Greek origins.
As a historian, as a traveller, I take a delight
in the secret lives of cities, in the hidden world under the streets,
where there are gems that explain so much.
This is definitely one of them.
There is an underground Istanbul.
It's full of hundreds of water cisterns
and this is the largest of them.
It was built in 537AD by one of the greatest of the Byzantine emperors, Justinian.
He wanted to make the city impregnable against siege
and for that it needed a water supply.
And this is it
but as you can see, Justinian never did anything by halves!
It's an extraordinary feat of engineering.
Constructed by 7,000 Roman slaves,
12 rows of 28 columns stretch away in every direction.
But as well as being an important Roman site,
there are also traces here of the city's even more ancient Greek, pagan past.
Right at the back, tucked away from immediate view,
are two gargantuan carved heads.
This is Medusa,
one of the most seductive but terrifying characters of Greek mythology,
one of the Gorgon sisters, famed for her beauty.
And she was in love with Perseus, the son of the Zeus.
But so was the goddess Athene,
who jealously devised a most terrible punishment for her rival.
Her hair was turned to snakes and her gaze would turn a man to stone.
Perseus chopped off her head
and used it as his own personal weapon of mass destruction,
to destroy his enemies.
Now, there might be a reason she's here like this.
Medusa's head was often used to ward off evil spirits
and she was deliberately placed sideways or upside down
because you didn't want to risk catching her gaze.
She might turn you to stone.
No-one knows exactly where these macabre heads originally came from.
But it's clear from their haphazard positioning
that they weren't specially crafted for this cistern.
And on further inspection, it's not just them.
If you look closely at these pillars
you'll see that actually none of them are the same.
And in many cases, the bases, the capitals, don't even match.
And that's because the builders of this place took bits and pieces
from different epochs of the city's earlier history.
Now, there are Roman parts
but there are also, most interestingly, Greek parts
and that's exciting because these are the last vestiges
of the original Greek town of Byzantium.
The diversity of all the pieces
that make up this beautiful cistern
is a wonderful illustration of the origins of this city.
It shows how a spectacular world capital like this was crafted
from early and obscure beginnings,
by borrowing, commandeering
and stealing the stones and stories of earlier towns and empires.
And in its earliest incarnation, this city was far from being sacred.
For its first millennium, Byzantium was just a fishing port
founded by Greek traders.
And rather than being renowned for its holiness,
this was a place famed for its drunken and licentious inhabitants.
The Byzantines were notorious in the ancient world
for their hard drinking and easy-going morals.
"They're besotted with drink," wrote one shocked traveller.
And worse than that, "they rent out their own marriage bed-chambers with their wives still in them."
Perhaps an early version of a Byzantine bed and breakfast.
A traveller to Greek Byzantium in the 7th century BC
could never have imagined that this sleazy port would one day become
one of the pre-eminent Christian cities in the world.
So what changed?
Well, in the first century BC, this part of the world had fallen under Roman control.
And in 196AD, Byzantium backed the wrong side
in a Roman civil war
and was taken by the Emperor Septimus Severus
after a bloody siege.
Septimus rebuilt it as a Roman town.
And Byzantium would probably have remained an affluent Greek fishing port
had it not been for the accession of an emperor
who was probably the most influential ruler in world history.
He left Rome and made Byzantium his world capital and holy city.
On 11th May 330AD,
these streets were feverish with excitement.
Everybody in Byzantium was rushing to the Hippodrome,
the entertainment centre of the city.
The Emperor Constantine was in town for a spectacular celebration.
This was their final destination. The Hippodrome.
430 metres long and 120 metres wide.
It's hard to imagine how impressive this once was
but I'm standing in Constantine's new Hippodrome,
a vast oval stadium
with a track around the centre for chariot racing.
High, tiered stands,
big enough to hold 100,000 baying fans.
Down there, Constantine sat in the Imperial Box
linked to the Imperial Palace
and he'd imported huge, new obelisks to stand in the middle,
ready for this special occasion.
Constantine was dedicating the old town of Byzantium to a new god
and what a dedication ceremony it was -
a magnificent procession,
in which the imperial statues of deified emperors were held aloft,
as they made their way round the packed stadium.
This was the moment that marked a whole new era for Byzantium,
in which the city would no longer be on the periphery of world history.
It would be dramatically reinvented
as the imperial capital of the entire Roman Empire.
And all at the whim of one extraordinary man ` Constantine,
a blunt-faced but visionary warlord
who hailed this metropolis as his "new Rome".
It was a daring move.
After a thousand years of grandeur, triumph and sanctity,
Constantine was turning his back on Rome
and betting everything on a faraway Greek fishing port.
So why had this emperor made such a geographical switch?
Constantine was a pragmatic power broker
and he had good strategic reasons to make Byzantium his new base.
The thriving heart of the Roman Empire was now in the east,
far from Rome, and its chief enemy was Persia,
so Byzantium, straddling Europe and Asia, was perfectly placed
to rule both.
But that wasn't the only reason.
20 years before this dedication ceremony,
Constantine had experienced a dramatic conversion to Christianity,
in the midst of a civil war to control the Western Empire.
The night before the decisive battle for the city of Rome,
he had a vision of a Christian sign in the sky
and the words, "by this sign thou shalt conquer",
and when he did conquer, he embraced Christianity.
It was a decision that would change world history.
The traditional view is that Constantine wanted to create
a pure, Christian metropolis, untainted by paganism,
totally unlike Rome.
And for that he chose Byzantium, and he called it Constantinopolis,
the city of Constantine.
He's remembered as one of the greatest heroes of Christian history,
the saintly ruler whose conversion transformed a minor sect
into the dominant faith in the West.
Or at least, that's how the story usually goes.
But here in the city he made his own,
there are intriguing clues
which suggest a more surprising view of this emperor and his motives.
This is one of Istanbul's most majestic mosques
but in the 4th century this whole area was dominated
by the greatest Christian monument in Constantinople.
Dedicated to the Holy Apostles,
it was built by Constantine in readiness for his own death.
I'm meeting historian and archaeologist Jonathan Bardill,
who believes it gives us a fascinating insight
into Constantine's real convictions.
Jonathan, what stood here originally?
Well, this site consisted of two buildings -
the church, a cruciform church,
and Constantine's mausoleum,
a circular building with a dome on the top.
On the inside of the mausoleum around the edge
were a number of niches
and those niches contained tombs for the 12 Apostles.
So presumably Constantine had the intention of gathering
the relics of the Apostles to put inside.
What does this tell us about Constantine himself?
Well, the striking thing about it is
that bang in the middle of the tombs of the 12 Apostles,
Constantine placed a 13th tomb
and that was his own sarcophagus.
Some scholars have suggested
that what Constantine was trying to say by doing that
is that he was the 13th Apostle.
I think he was trying to say something much more radical.
It's this mysterious 13th sarcophagus that may hold the key
to the emperor's true and possibly heretical beliefs.
But there has been much controversy about its exact location.
Some claim it's one of these vast sarcophagi
now outside the Istanbul Museum,
which once contained the remains of Byzantine emperors.
But Jonathan thinks it's somewhere else entirely.
This building stands on the site
of what was the oldest church in Istanbul, built by Constantine,
and dedicated to Holy Peace.
And hidden away in its neglected courtyard may lie the answer.
So this is what I think is the last resting place of Constantine the Great.
That's exciting. Now, tell me why you think that?
Well, a number of reasons.
The first one is that if you look,
you can see that there are holes drilled into the sarcophagus. Yeah.
Well, we know that Constantine's sarcophagus was covered
with a splendid cover interwoven with gold,
according to one author.
Now, I suspect that what these holes are are places for brackets
in which a curtain of woven material could have been attached.
But what I think is really the clincher is round the corner.
If we look at the gable end of the sarcophagus
you can see this symbol
and the best way to explain it, in my mind,
is that it actually represents Constantine's standard,
the standard that we know he took into battle
that was based on the cross, with the Chi Rho monogram,
the symbol of Jesus Christ, in a wreath on the top.
So what does that mean?
Well, you have to remember
that this sarcophagus was in the middle of the relics of the 12 Apostles.
I don't think Constantine was claiming to be a 13th apostle.
I think he was claiming to be Jesus Christ.
Wow! That's quite a claim.
It is, but perhaps not so extraordinary in the context of late emperors,
many of whom thought they were close to being divinities.
But clearly some people thought this was a particularly blasphemous claim.
And we know that because it seems that Constantius, his son,
actually reorganised the burial site
to make sure that Constantine was no longer in the middle of the Apostles.
He clearly felt that the claim was much too great
and too close to heresy - he had to change it.
It's a controversial theory.
Constantine was baptised on his deathbed,
confirming his Christian faith.
He clearly believed in the Christian God.
But perhaps he was still very much part
of the pagan world of deified emperors in which he grew up.
Whatever the idiosyncrasies of Constantine's personal beliefs,
his embrace of Christianity had changed the city's fortunes forever.
In life, he'd created the Christian city of Constantinople.
In death, by choosing to be buried here,
he was making a powerful statement
about how important the city had become.
But Constantinople's meteoric rise to power was not unchallenged.
This might now be the political heart of the empire
and home to its emperors,
but in terms of its status as pre-eminent sacred city,
Constantinople had powerful rivals.
Alexandria in Egypt and Antioch in Syria had
far stronger claims to holiness.
And it was here, on the site of Constantine's Church of Holy Peace,
that in the summer of 381AD,
a fight to consolidate this city's sacred power and status played out.
When a general named Theodosius, a devout Christian, was elected emperor,
he was determined to impose Christianity as the state religion -
one faith, one empire.
But first he had to settle the raging controversy
that threatened to tear apart all of Christendom -
was Christ man or was he God?
So he called a council.
But as the bishops gathered from across the empire,
Theodosius faced a major obstacle.
Although political power now lay in Constantinople, the new Rome,
an imperial capital,
religious decisions were still very much the prerogative
of the old Rome.
To avoid his orders being challenged by the Western Papacy at every turn,
Theodosius needed to concentrate secular and sacred power in one place
and to do that, he needed to elevate Constantinople's holy status,
so it could challenge Rome's sacred authority.
But that wasn't going to be easy.
The city was in thrall to a heresy.
It was the work of a charismatic Egyptian priest named Arius,
whose ideas struck at the heart of the Christian faith.
He passionately denied the divinity of Christ,
claiming instead that Jesus was a mere human.
For early Christians, this was a matter of life and death.
If Arius was right and Jesus was just human,
then his death wouldn't be enough to save us from our sins.
To do that, Jesus had to be both human and divine.
Those were the stakes - salvation or damnation.
Arius's beliefs sent shockwaves through the church
and he was condemned as a heretic.
He came to a rather messy end.
While walking through the streets in the centre of Constantinople,
Arius was taken short, and to his horror,
his intestines, liver and spleen haemorrhaged out
in a heretical splurge.
His enemies might well say that this faecal end was no more than a just comment
on his appalling ideas.
But his ideas didn't die with him.
They spread like wildfire across the Christian world.
Theodosius was determined to crush this heresy once and for all.
First he sacked the Arian Bishop of Constantinople
and then the Council condemned Arianism,
affirming that Jesus was both God and man.
With Constantinople free of heresy,
the way was clear for Theodosius to turn his attention to the city's promotion.
Theodosius persuade the Council to vote Constantinople up the hierarchy
of Christian cities,
so that now it would be second only to Rome itself.
The Bishop of Constantinople, it declared, shall have
the prerogative of honour after the Bishop of Rome
because Constantinople is the new Rome.
This was the moment that Constantinople's status
as one of the world's most important holy cities was confirmed,
challenging even Rome's pre-eminence
as the centre of power in the Christian world.
Unsurprisingly, it wasn't popular.
Many people still regarded Constantinople as an old Greek fishing port
with barely 50 years of Christian history.
While Antioch, Alexandria and, of course, Rome had been founded
by Jesus's own disciples.
They had far more distinguished Christian histories than Constantinople.
Papal representatives weren't even present at the conference,
so Rome received news of Constantinople's promotion by letter,
which it rejected outright.
Alexandria voted against it
and the Bishop of Antioch couldn't have made his view clearer.
He dropped dead in the middle of the conference.
As the bishops dispersed, Theodosius had achieved his aim -
to centralise secular and religious power in one place.
But Constantinople's supremacy would be frequently contested
during the next 800 years
and provoke rivalries and tensions with other Christian cities
that would never heal.
In the wake of the Council of Constantinople,
the emperors could now promote a state Christianity -
one empire, one God, all ruled from one capital.
Constantinople itself had been officially proclaimed a holy city.
Just like Rome.
Well, not quite.
While Rome had St Peter's
and Jerusalem had the Church of the Holy Sepulchre,
Constantinople still lacked the sort of sacred landmark
that defines a city.
It was to take an imperial couple of soaring ambition,
whose reign was a story of vanity, revolution and sexual scandal,
to raise the church that still dominates this city - Hagia Sophia.
The Emperor Justinian and his wife Theodora
came to power in the early 6th century.
And tucked away down this quiet back street is
one of the first churches they commissioned.
Nicknamed Little Hagia Sophia because of its similarities
to their much grander masterpiece,
it gives us a fascinating insight into the unique fusion
of holiness, power and prestige that is peculiarly Byzantine.
In the 16th century, the building was turned into a mosque
and since its conversion,
much of the original decoration has disappeared
but there are still glimpses of how it once looked.
Look at these columns here - at the top of them is a circular stamp
and that is actually the imperial monogram of Justinian and Theodora.
But even more exciting, though very hard to see,
is the Greek inscription around this colonnade
which tells us a lot about how this particular Emperor and Empress
wanted to portray themselves,
wanted to be remembered by history.
And from the words inscribed here,
you'd think they were paragons of Christian godliness.
The inscription reads,
"the sceptred Justinian builds this splendid abode
"for the servant of Christ."
But it really heaps lavish praise on Theodora.
"Theodora, the God-crowned, adorned with piety,
"toils ceaselessly to nourish the destitute".
This Theodora was clearly a paragon of Christian virtue.
But the reality was more complicated.
Justinian and Theodora had spectacularly risen to power
from backgrounds that were neither pious nor imperial.
Religious buildings have always projected the glory
of the kings who built them.
Justinian and Theodora followed suit.
But they did so more magnificently than anyone else.
And they had good reasons to parade their piety.
They both had histories they were keen to rewrite.
The main source for the lives of Justinian and Theodora
are the books of a 6th-century writer, Procopius.
And his work offers a far more lurid insight into their past.
Procopius was one of the court historians of the Imperial couple
and he wrote several books in praise of their glorious deeds.
But he also wrote this ` The Secret History `
and it tells what he really thought of them.
One has to approach it a bit like a Byzantine tabloid newspaper.
Probably about 75% of it is true.
And it portrays Justinian as a knave and a poltroon,
greedy, vindictive, and puny.
But it really goes to town on Theodora.
She was born a daughter of one of the Hippodrome's bear masters.
As a teenager she became a burlesque showgirl.
She was notorious for her erotic enthusiasm,
taking on entire dinner parties of guests and, Procopius adds,
all the servants.
Roman law banned men of senatorial rank from marrying actresses
but Justinian was so in love with Theodora
that he had the law changed.
Their relationship was to last over 20 years.
And when Theodora was reborn as Empress,
she and her husband humourlessly and sanctimoniously embraced their role
as sacred rulers of the entire Christian world.
Theirs was a partnership that would endure
some of the most deadly crises faced by any emperor.
And the greatest battle they fought wasn't against a foreign power.
It was against their own city.
It started with a riot and it ended with a bloodbath
and the building of the most splendid church
in the entire Roman Empire.
And it all unfolded right here.
In 532 this was the site of a bloody rebellion
that almost led to Justinian and Theodora's downfall,
only five years after they'd claimed power.
The main show at the Hippodrome was the chariot racing.
There were two main teams, the Greens and the Blues,
whose savage rivalry divided the city,
and often broke out into open gang warfare.
Justinian sentenced some Blues and some Greens to death for murder.
But in doing so, he united the two factions against him,
an unpopular decision for an unpopular Emperor.
That night at the Hippodrome, the Emperor was booed
and the mob rose in open revolution.
The rebels quickly seized control of the streets, hailed a new Emperor
and set fire to the imperial district.
In the chaos, Justinian was besieged in his palace.
Justinian was about to flee but Theodora gave him courage.
She said it was better to die in imperial purple
than it was to live without it.
Together, they summoned their favourite general, Belisarius,
and he and his soldiers stormed the Hippodrome and killed 30,000 people.
They were buried where they fell.
Justinian, the shrewdest of leaders,
converted the tragedy into his own triumph.
Justinian regarded his victory over the rebels
as evidence of divine providence,
and out of the ashes, he started to raise the building
that more than any other has come to define
the sacred and imperial prestige of the city.
It was, of course, Hagia Sophia, the Church of the Holy Wisdom.
And it was like nothing that Constantinople had ever seen before.
The interior was studded with four acres of golden glass cubes.
The columns were transported from Egypt and Ephesus.
But its crowning glory was its incredible dome,
curving 110 feet from east to west
and soaring 180 feet above the marble floor.
The historian Procopius marvelled
that it "does not appear to rest upon a solid foundation
"but to cover the place beneath
"as though it were suspended from heaven by the fabled golden chain."
This is utterly splendid and it really takes the breath away.
But that was the point.
Size mattered to Justinian
and when he commissioned his architect,
he asked for two things.
He wanted it to be huge and he wanted it to be unique
and as you can see, he got both.
You might say this is an example of megalomaniac gigantism
but if so, it's the most successful example in world history.
I think it's the most wonderful building in Europe.
It's just lovely to be here.
For the next 900 years,
this was the supreme temple of Orthodox Christianity,
and the seat of the Patriarch of the Eastern church,
the equivalent of the Pope in Rome.
More than that, it was the largest religious building in the Christian world.
The church was dedicated on 27th December 537
and it was a clear statement of Justinian's renewed grip on power
and on Constantinople's claim to rule the world.
Although his reign had started inauspiciously,
Justinian enjoyed astonishing success.
Rome and the Western Empire had long since fallen to the Barbarians.
But he and Theodora had set out to recover
the lost territories of the Roman Empire
and they'd succeeded, even taking Rome itself.
In the process, they created a Byzantine Empire
Centred around his crown, his city, his Hagia Sofia,
Justinian believed that he had united Christendom
as Universal Emperor and Jesus's regent on earth.
But it wasn't to last.
In 548 the Empress Theodora died and Justinian never recovered.
He reigned for another 20 years
but it would have been better if he'd died with her.
The Persians invaded, Slavs and Huns marauded.
The treasury was empty.
And earthquakes cracked the dome of his beloved St Sophia.
Overall, the Empire was overstretched and the Emperor was old and hated.
The Emperor died aged 83, having reigned for more than 38 years,
and was laid to rest in Constantine's Church of the Holy Apostles,
next to Theodora.
Justinian's reign was judged rather harshly by contemporaries.
"He caused nothing but noise and troubles," said one,
"and he should be judged in hell."
But in truth, he had made this city the envy of the world.
As one Russian visitor later put it,
"You do not know if you are in heaven or on earth.
"For on earth there is surely no such splendour and beauty
"and we have not words to describe this.
"We know only that here God dwells among men."
Justinian had continued to realise Constantine's vision
of Constantinople as the new Rome.
He built more than 40 churches
and the city now had its own St Peter's.
But it still lacked the very thing
that gave Rome its claim to be the pre-eminent holy city.
Its own protector and saint.
St Peter's was built over the final resting place
of the bones of Saint Peter himself, Jesus's closest disciple,
and it based its sacred legitimacy on that.
Constantinople had an amazing collection of relics
but it just couldn't top Rome.
It took a desperate and unprecedented crisis
in the early 7th century
to finally deliver a heavenly guardian
the city could call its own.
And it was no mere Apostle. It was the Mother of God herself.
After Justinian, the Empire almost fell apart.
Generals seized power in bloody coups,
mobs rioted, and the entire East fell to the Persians.
But in 626, Constantinople faced its most deadly threat.
A coordinated assault
that would first have been glimpsed from the Roman walls
that stretch right across Istanbul's land boundary.
For the Byzantines manning these very walls on 29th July 626,
it must have seemed like every nightmare had come true.
For they faced not one besieging army but three,
by both land and by sea.
Before them here, they faced the Avars,
a vast horde of ferocious horsemen from the Eurasian steppes.
Over there, the glistening breast plates of the magnificent cavalry of Persia.
But most alarmingly of all, here on the Golden Horn,
the water was dark
with the ships of the shaggy-haired Slavs from the north.
It must have seemed as if the whole world
had come to destroy Constantinople.
For those trapped inside, it must have been truly terrifying.
As the battle began, catapults hurled rocks.
Siege towers were deployed
and siege engines smashed against the walls.
The city's water supply was cut off as the enemy destroyed the aqueduct.
And off the coast the Slav fleet began its approach.
For ten days the Byzantine capital faced formidable attack.
Constantinople was surely doomed.
Their best general, the heroic Emperor Heraclius, wasn't even in the city `
he was far in the east, fighting the Persians.
It must have seemed as if there was no way out.
The General and the Orthodox Patriarch,
to whom Heraclius had delegated power in his absence,
took control.
In desperation, General Bonus launched the Byzantine fleet
to stop the advance on the water,
whilst on land the Patriarch Sergios began a petitioning of the divine.
HE SINGS
The Patriarch led the desperate people
in procession around the walls,
holding icons of Christ chanting hymns,
and begging for the intercession of the Virgin Mary.
Only she could save the city.
And what happened next did indeed appear miraculous.
Eyewitness accounts suggest that the Patriarch's prayers were answered.
The Khan of the Avars was amazed to see a woman on the ramparts,
leading the defence of the city.
But it wasn't just any woman, it was the Virgin Mary herself
and she'd come to save Constantinople.
Against the odds, the Byzantine navy defeated the Slavs,
whose fleet was scattered by a storm.
The Avars and the Persians retreated.
And all over the city shrines dedicated to the Virgin Mary sprang up,
celebrating her role as guarantor of imperial victory.
Constantinople now had a protector to rival Rome's.
But the glory of Heraclius' dynasty was short-lived
and stained by his depraved and incompetent descendants.
And the most monstrous was Justinian II...
..notorious for his sadism, degeneracy and extortion,
as well as his rows with Rome.
In 795 he was overthrown
and his punishment typifies the merciless politics and elaborate cruelty
that was coming to define Byzantine rule.
And it was in a part of the Hippodrome
few ever get to see, directly below the stadium,
that Justinian's hideous punishment began.
I'm especially excited to see this
because this is the Sphendone,
in effect, backstage at the chariot racing under the Hippodrome.
The Hippodrome was so enormous that it had a large substructure
where they used to marshal the charioteers and the horses
before they went out into the stadium to race and die.
But this place also had an especially dark and gruesome role in Byzantine life,
and that's why I'm especially enthralled to see what it's like.
Wow! What a place!
This labyrinth of passages snakes beneath the arena
where Justinian II was led in chains.
He was about to endure one of those horrible punishments
that really epitomised the vicious and labyrinthine nature of politics
that today we describe with one word - Byzantine.
First he had his nose cut off, sliced through.
And that is a practice known in Greek as rhinokepia.
And then he had his tongue amputated ` elinguation it's called.
Now, Byzantine emperors were meant to be physically perfect
and so the idea here was
that Justinian II should never be allowed to reign again.
He was banished but like a villain in a horror film, he just kept coming back.
In 705 he returned to power.
Now known as Emperor Slit-Nose,
he wore a golden mask to hide his deformity.
He needed an interpreter to translate his tongueless gruntings
and once again, he reigned with terror.
And it wasn't long before he was again absolutely hated.
He was overthrown and this time they took no chances.
He didn't just lose his nose, he lost his head, too.
After Justinian's comeback, fallen emperors no longer lost their noses or tongues.
From now on, they were either blinded or killed.
And as Constantinople's resources were squandered
on grotesque emperors and palace coups,
the Byzantines were losing their empire
to a dynamic new force
that would threaten the very existence, not just of the city,
but of Christendom itself.
MUEZZIN CALLING
The armies of the new revelation of Islam,
commanded by Mohammed's successors,
burst out of the Arabian peninsula
and invaded the Byzantine Middle East.
By 638 they'd taken Jerusalem and most of the Eastern Roman Empire.
In 717 they were at the gates of Constantinople in massive force
and settled down to besiege the city.
The Byzantines measured divine favour by success in war,
so the energetic gallop of the Arab armies raised difficult questions.
Was the city cursed?
Had the Christian God forsaken them to back the followers of Mohammed?
And if so, why?
Twice the Byzantines managed to survive sieges of the city
but for how long?
It had been a close-run thing
and for one emperor in particular, Leo III, too close.
He saw imperial military weakness as a sign of God's displeasure
and a symptom of the people's passion for holy images - icons.
Bizarre as it may seem,
the battle of the icons would be the most rabid and vicious controversy
in the entire history of an empire obsessed with religion.
In modern Istanbul,
only a tiny surviving pocket
of the Eastern Orthodox Christians who once dominated Constantinople
still live and worship here.
Once the city was almost entirely Christian
and they now make up less than 1% of its population.
This is their Patriarchal church `
an 18th-century building dedicated to St George.
They may no longer rule this city
but their ancient rituals still reverberate
with echoes of the religious conflicts of the Byzantine Christian world.
It was a world where believers were renowned for their devotion to icons -
holy images usually painted onto wood
and showing Jesus, Mary or the saints.
But they weren't just pictures.
For Byzantines they were sacred and powerful in their own right.
They were windows onto the divine.
Their veneration is still a defining part
of this mystical Orthodox tradition.
Every Orthodox church has an icon screen
separating the nave from the altar.
The images are processed and kissed by the holy Patriarch
and the faithful follow suit.
But in 726, Leo III decided
the veneration of these holy objects had gone too far.
Their cult had reached fever pitch proportions -
they were credited with healings
and people scraped off their paint, drinking it like medicine.
In some cases, icons even served as godparents at baptisms.
For Leo and his like-minded bishops,
the issue was whether such extreme veneration was acceptable to God.
After all, the second of the Ten Commandments clearly stated
that graven images shouldn't be worshipped.
The empire's military losses to the Muslims `
who banned all use of images in their worship -
led Leo to a controversial conclusion.
Perhaps it was the intense attachment to these icons
that was causing the empire's defeats.
Leo ordered the destruction of all the holy images
and the punishment of anyone who refused to obey him.
Reminders of the violence of what became known as iconoclasm can be found
in the Istanbul Archaeology Museum.
What we have here are two stone icons,
from the Church of St Polyeuctos,
one of the most magnificent in Constantinople.
And you can see immediately
that the faces have been completely chiselled off.
You can just about tell that this is the Virgin and Child,
this is an Apostle.
But otherwise the features are gone.
And from looking at this you can just get a sense
of the savage violence of iconoclasm.
Now, these are stone but if they were wooden icons they were burnt.
If they were statues they were smashed.
If they were fine mosaics they were plastered over.
And it wasn't just images that suffered.
Those who defended their sacred icons
had to endure even greater torment.
Monks who refused to hand over their icons were taken to the Hippodrome,
made to hold hands with harlots
and then spat at by a baying iconoclasmic mob.
Monasteries were raided
and churches who refused to hand over their images
were attacked by the imperial police,
where the resisting monks were put to the sword.
The battle over holy images raged for an entire century
with a ferocity that finally burnt itself out.
And it was the icon lovers who prevailed.
Their victory is commemorated here in Hagia Sophia,
in spectacular works of religious art.
And I'm meeting art historian Robin Cormack
to learn more about what led to iconoclasm's demise.
Robin, why did iconoclasm end?
Well, when iconoclasm ended in the 840s,
the political climate had changed.
The Arabs had moved their capital to Baghdad,
there was no longer a Muslim threat.
The theological position had changed.
The churchmen who had been opposed to images had all moved on.
A new group came in, so there was an alignment of politics and the church
to bring the icons back and they did it.
On Easter Sunday 867, the triumph of the holy images was celebrated
and Hagia Sophia was transformed by new and splendid mosaics,
inaugurated in a magnificent service of thanksgiving.
The great day of celebration after iconoclasm came
with the unveiling of the Virgin and Child that we can see today.
The Emperors were here.
The public was here and the Patriarch gave a sermon
pointing up into the apse there,
and he said this is the beginning, the first day of Orthodoxy.
And around the apse was the inscription,
of which we can see the first words and the last words.
And they said, "The images which the heretics cast down,
"pious emperors restored again."
It was a moment that altered the whole way
in which this church spoke to its people.
Symbolic crosses were replaced
by glorious figurative images of the Christian story.
And it wasn't just the building.
The end of iconoclasm defined
the whole nature of Eastern Orthodox worship.
The Byzantine church became once more identified by images.
Free of the wasteful frenzy of iconoclasm,
the empire, led by a run of brilliant soldier emperors,
recovered, expanded and thrived.
But the conflict over holy images had caused lasting damage,
not just to the icons of the city,
but to the relationship between the Eastern and Western churches.
Throughout the controversy,
the Western church had fully defended the use of icons,
contributing to an ever-deepening rift.
Ever since Constantine had made it his new Rome,
the two cities had been rivals.
But for the last 50 years they'd been outright enemies.
They disagreed on the powers of the Papacy
and arcane questions of ritual and doctrine.
And iconoclasm had just made things even worse.
In 1054, matters came to a head.
On July 16th, Papal legates burst into the service
here in Saint Sophia
and laid a sentence of excommunication right on the altar.
Although no-one could've foreseen it,
this would alter the course of Constantinople's future...
and ultimately lead to catastrophe for this holy city.
Seven centuries after Constantine's transformation
of this holy city, Constantinople faces fresh onslaughts -
from the Muslim Turks and from Rome.