In the Belly of Byzantium: The Subterranean Spaces of Istanbul

Istanbul is one of the most visited cities in the world – and rightly so. It offers breathtaking mosques, imperial palaces, monuments, markets and bazaars, all wrapped up in Turkey’s famously warm hospitality. Many of these sites are located around the Sultanahmet district, the tourist centre of the city and a hotbed of ancient history.

Nevertheless, there is a sub-level to this place; a warren of tunnels and cisterns and passages and tombs, only a small portion of which is accessible to visitors.

Byzantium-1-Istanbul Day 2I’ve been to Istanbul around a dozen times now – sometimes alone, sometimes with others – and on each new visit I try to explore a different area. For the most part I’ve stopped going to Sultanahmet altogether; the crowds, the cameras, the con artists can all get a bit too much after a while. In the past I’ve written about Islamic tombs and pilgrimage sites in outlying districts of the city, as well as looking at Istanbul’s first power station

But this post is about Sultanahmet. It is about the old heart of Istanbul, the heart of Constantinople before that; it is about the tourist district, but more significantly – the subterranean realms therein that tourists rarely see.

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18 Hundred Years of Tourism

In 2010, Istanbul received 6.9 million foreign visitors. By 2011 it was 8 million, and that figure still seems to be rising. Most of that traffic is headed for Sultanahmet. Named after Sultan Ahmed I, an early 17th century ruler of the Ottoman Empire, this district features some of the city’s most famous attractions: Topkapı Palace, the Hagia Sophia and the Blue Mosque, the Grand Bazaar and the Byzantine Hippodrome.

Byzantium-2-Istanbul Night 6The last of these has been drawing the crowds into Istanbul – then, ‘Byzantium’ – since as early as 203 AD. The Hippodrome was built by Emperor Septimius Severus at the heart of this provincial town; but the city later grew, when in 324 AD Emperor Constantine the Great moved his capital here from Rome. Byzantium became ‘Nova Roma,’ briefly, before adopting the emperor’s own name as ‘Constantinople.’

The hippodrome was an early circus, a sporting arena that hosted horse and chariot races on a central oval surrounded by tiered seating. Under Constantine, the hippodrome flourished. It was enlarged and renovated during the 4th century, estimated to have measured 450m in length and with stands that could accommodate crowds of up to 100,000 people. The centre of the racetrack – the ‘spina’ – was filled with statues and monuments. It was a lively social hub, and a great deal of money was spent on the races in the form of bets; these even became political in nature, as different race teams earned the sponsorship of vying political parties within the government.

Following the foundation of the First Bulgarian State in 681, Byzantium would be drawn into fierce territorial struggles; the Byzantine-Bulgarian Wars continued, on and off, for 675 years, and as the Bulgarian Empire grew in the north it would begin to eclipse the waning strength of Constantinople.

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Byzantium-6-Nakkas Sarnici 3Then, in the early 13th century, the Byzantine Empire was sacked by Western Europeans during the Fourth Crusade; a beating from which it would never fully recover. By the time Constantinople fell to the Ottoman Turks in 1453 the hippodrome – the social heart of the city under Byzantine rule – was allowed to fall into ruin and obscurity.

Today the hippodrome is largely vanished, its central racetrack paved over to form Sultanahmet Square. The surface of the city has risen by 2m since then, so that the monuments, those which survive, stand in deep wells landscaped into the new plaza. Of the many works of art that once lined the central spina, three remain in their positions today: the 10th century ‘Walled Obelisk’ rises from the square, while the ‘Serpent Column’ – a three-headed spiral crafted to celebrate Greece’s victory against the Persians – still stands, albeit, now minus its heads.

Then there’s the Obelisk of Thutmose III; a pink granite obelisk, not unlike Cleopatra’s Needle in London… though this one came from Luxor, first raised in 1490 BC and carried from Egypt to Constantinople in 390 AD. It stands today on the same marble pedestal it has occupied for 16 centuries, its top-most section original and intact; a 3,500-year-old monument patiently watching the city change around it.

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The best preserved relics of Constantinople are not to be found on the surface of the city, however. The most famous of these subterranean sites lies right in the centre of Sultanahmet: an ancient cistern, Roman city infrastructure now renovated to serve as a carefully managed tourist attraction.


The Basilica Cistern

The Yerebatan Sarayı (or ‘Sunken Palace’) is the best known – and certainly the best kept – of Istanbul’s subterranean wonders. Still, it’s surprising quite how many visitors to the city walk on past, or rather, above the site without any knowledge of its existence.

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Better known to Westerners as the Basilica Cistern, this structure was used for the storage of water during the 6th century reign of Emperor Justinian I. It is believed to have held as much as 80 million litres of water – clean, filtered water which could be drawn up above, through pumps and wells scattered around the Great Palace of Constantinople. It was but one of several hundred cisterns beneath the city, although the Basilica Cistern remained in use much later than some of its sisters – serving the palace at Topkapı long after the Ottoman conquest of Istanbul.

But then, unlike many of the city’s other cisterns, this one was never ‘lost.’ It received extensive restoration work in the 18th century, and again in the 19th century. In 1985 a serious renovation project dredged some 50,000 tons of mud from the cistern, after which wooden walkways were installed between the pillars.

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It was towards these walkways we were heading: through a stone gatehouse on the surface, just along the street from the Hagia Sophia, past the ticket booth and down a series of fifty-two stone steps into the bowels of old Constantinople.

Rather than an archaeological site, a relic or a ruin, the Basilica Cistern had more the feel of a temple about it. This vast, vaulted space beneath Sultanahmet was filled with pillars – 336 of them in total – that neatly stood in rows, rising up out of the shallow water. There was music drifting about the columns, a distant orchestra playing something minimal and middle-Eastern, the sort of music that I would imagine once filled Ottoman banquet halls.

The lighting too, down here, was minimal; jets of red and orange and yellow, spotlights set on the feet of pillars to paint them like tongues of fire; but dim enough to maintain the aura of darkness – and set these burning stones against a void of inky black.

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There were other visitors here, quite a few of them, though the sound they made seemed to echo into nothing; an indistinct murmur of voices that somehow only added to the sense of hushed reverence. It was hard to comprehend that this space – so elaborately built, so lovingly restored – had been designed not as a cathedral, but rather, to serve the role of invisible city infrastructure.

Stepping onto the boardwalk, the wood creaked beneath my feet with a satisfying warmth. I heard a splash, and ripples, and glanced over the railing to see coins glinting dully from the submerged floor beneath. Then the coins disappeared, one dark body then another passing over them like clouds across the moon. The cistern, I realised, was full of fish.

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Byzantium-3-Basilica Cistern 8Rising to a height of 9m, the columns of the Basilica Cistern dominate the space – a distance of almost 140m from one end to the other. They also vary in style. These were recycled parts, and it is believed that they would have been brought to Constantinople from all corners of the Byzantine Empire. These grand pillars were the off-cuts, the spoils of lost cities repurposed to build the caverns beneath the capital; Ionic, Corinthian and Doric, marble or granite, with capitals in a range of differing fashions.

Most striking amongst the columns however, were those that lurked in the northwest corner; two pillars that grew from the stone faces of gorgons.

It is not known where the Medusa heads originated from, though the significance is clear – in a newly Christianised city, the characters associated with previous belief systems would soon have been relegated to the level of scrap material. A local tradition suggests that the faces were positioned sideways and upside-down, in order to negate the petrifying power of the gorgon’s stare.

I was stood by the sideways Medusa, admiring the stone features, when I felt a tremor in the wood beneath my feet. Looking up, I saw a horde approach: Japanese tourists, their camera-fingers twitching in rapid-fire motions as they came down the elevated walkway towards me.

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Byzantium-3-Basilica Cistern 10Soon the pillar was almost entirely lost from sight as the tourists crowded about it, flashing at the gorgon with their cameraphones.

Retreating, I found another interesting feature not far off: a green pillar set with the carved shapes of eyes and teardrops. According to ancient texts, the tears were placed in tribute to the 7,000 slaves who laboured on the cistern… several hundred of whom, it is said, also dying in the process.

By the exit, the Cistern Café sold overpriced drinks beneath a garish neon sign. Its presence here in this sacred space was incongruous, and strangely wonderful.

The cistern is only half of the story however, and I was curious to look at the waterways which once fed it. Great stone aqueducts, feats of early engineering that rise now dry and dusty on the edge of the city centre.


Roman Waterways

The Valens Aqueduct is known in Turkish as the ‘Bozdoğan Kemeri,’ or ‘Aqueduct of the Grey Falcon,’ and was put into use in 368 AD under the Roman Emperor Valens.

Byzantium-4-Aqueduct 2The aqueduct originally transported water from streams in the hills, into the centre of the city where it would be stored in open reservoirs and hidden cisterns such as the Basilica. A drought struck the country in 382, and so Emperor Theodosius I extended the line; sourcing water from the northeast, in the region of the Belgrade Forest. In time the Valens Aqueduct would come to serve as just one stretch of a complex water movement system totalling more than 250km of canals and aqueducts – the largest such network in the world at that time.

Under the Byzantines, the aqueduct was well maintained; feeding fresh water to the Basilica Cistern, to the Baths of Zeuxippus and the Great Palace of Constantinople. When the Ottomans conquered the city in 1453, Sultan Mehmet II repaired and extended the system to supply Eski Sarayi (‘The First Palace’) and Topkapı Palace. Again it was extended, during the 16th century under Sultan Suleiman I: this time adding more lines, to increase the flow of water into the city. Though parts of the aqueduct were pulled down in 1912, it remained in use until as late as the 1950s.

The Valens Aqueduct was a terrific feat of Roman engineering. Built from brick and ashlar blocks, it rose to its highest point at 29m – and from there fed water back down towards Sultanahmet, at a constant slope of 1:1000. Though it’s largely dried up these days, a section of some 920m still remains; its arches trampling over shops and cemeteries, stepping nimbly across the busy Ataturk Boulevard.

Byzantium-4-Aqueduct 1To reach the aqueduct, we travelled to the city’s ‘third hill.’ From the tram stop we passed through a cemetery, between narrow tombs shaped like scimitars, gravestones topped with carved turbans; around the corner of the Şehzade Mosque that rose above the tombs, grey-blue marble bubbling up into domes and towering minarets. At the rear of the mosque we stumbled across a gathering – walking straight into a wedding, from the look of it: several hundred people sat around banquet tables on the lawn.

Leaving the festivities behind we made our way out down an alleyway that folded between older buildings on the edge of the well-kept gardens of the mosque. That’s where we caught our first glimpse of the aqueduct – a stone arch at the far end of the passageway, innocuous enough as seen from here, but building into something old and ancient.

Turning the corner, beneath the arch, the aqueduct looped off down the street: a ribbon of old stone, hopping cars and fences, growing taller with every bound. We followed it as closely as we could, through back streets and car parks, through narrow alleys lined with rusted vehicles, past playgrounds where children kicked balls around. Finally we turned one last corner, passed beneath an arch in the Roman aqueduct and came out on a square of park overlooking a six-lane highway.

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Cars, buses and taxis swarmed past, moving beneath the grand arches, in and out, humming like bees around a hive. It was a strange and beautiful juxtaposition: Ataturk Boulevard, one of the city’s main roadways, intersecting with the waterways raised by Romans some 1,600 years before.


The Binbirdirek Cistern

The Basilica Cistern is the largest (known) cistern beneath Istanbul. The city’s second largest, meanwhile, is the nearby Binbirdirek Sarnıcı… sometimes referred to as the ‘Cistern of Philoxenos.’ Its name, in Turkish, means ‘1001 Columns’; though in reality, the Binbirdirek Cistern features just 224.

The cistern was built in the 5th century, beneath the Palace of Antiochus, though it fell into disuse after the 15th century Ottoman conquest – and only in the 17th century was it ‘found’ again, when a new palace was constructed on the site above.

Byzantium-5-Binbirdirek SarniciLast time I was in the city, we went looking for this Cistern of Philoxenos. I had a map for the entrance, but it led to a dead-end. As we stood comparing lines to streets, turning the map around different ways, we were approached by a man who’d been stood on a nearby corner.

“What kind of carpet are you looking for?” he asked, skipping any kind of preamble and instead diving head first into the middle of his sales pitch.

“How close are we to Binbirdirek Sarnıcı?” I replied, employing a similar tactic. The man smiled, and offered a deal.

“Why not come look at my shop first… Just to look! And then I’ll take you there.”

We were not in the market for a carpet that day, though; I told him as much, and the vendor simply gave a resigned shrug to a building that rose on the far side of a nearby square.

“The cistern is closed anyway,” he said. I examined the structure – steel and white plastic, no sign of entrance – only a locked door beneath a faded sign that read: ‘Binbirdirek Sarnıcı.’

Later I’d learn that there was another entrance to Binbirdirek, to the Cistern of Philoxenos… I wondered if the rug merchant had known that, and if he had simply been punishing my lack of interest in his wares.

Nevertheless, later that afternoon we did find our way inside another of the city’s ancient reservoirs.

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The Nakkaş Cistern

There is a cistern around the back of the Blue Mosque, beneath a narrow street that winds around and down towards the Sea of Marmara; located in the basement of the Nakkaş carpet shop. Walking in through the grand, double glass doors of the carpet emporium, I was greeted by a man in a sharp, tailored suit. I was ready to decline the sales pitch that I was sure he would deliver – by now, I’d become accustomed to it – but it never came.

“Sarnıcı?” he asked me, with just the slightest incline of his head. I nodded, and he made an elegant gesture towards the stairs tucked away at the back of the carpet showroom. We passed through the expensive displays, and disappeared down the steps towards a discrete basement level. It could have been a scene from any spy movie.

Byzantium-6-Nakkas Sarnici 2The Nakkaş Cistern – for want of a better name – is smaller than some of its cousins, with a location that would suggest it had supplied the Great Palace of Constantinople. Descending the narrow stairs beneath the carpet shop, the cistern opened up before us: arched roof and thick pillars lit in orange and yellow, information panels studded along either wall… and a projector screen at the far end showing animated 3D models of the former hippodrome.

The pillars running down either side were a mismatch of styles and eras. Like the Basilica Cistern, this space was apparently not designed to be looked at: smooth columns, fluted shafts, a range of different capitals that appeared to have been formed, most likely, from the offcuts of the city’s overground architecture.

It is believed that Constantinople once featured several hundred cisterns. There is another accessible cistern under the district of Eminönü; there are open-air remains at Bakırköy too, the so-called ‘Cistern of the Hebdomon.’ The Şerefiye Sarnıcı can be found behind the former Sultanahmet Belediyesi building, while the Sultan Sarnıcı in Çarşamba has been repurposed now as a restaurant. In total there are something like 24 still visible: some above ground, some below; some maintained as tourist attractions, others largely derelict.

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But it isn’t only cisterns that open in unseen space beneath the streets of Istanbul. There are sacred springs, as many as 200 of them, some of which open into subterranean grottos; such as the spring behind the Hagios Demetrios at Kuruçeşme. There are even subterranean mosques – the Yeraltı Cami is one, located beneath the backstreets of Karaköy.

But these sites are known; many are in operation, even, as popular tourist destinations. Still more interesting to me were the legends – the rumours and urban myths about deeper networks of tunnels constructed beneath Constantinople, ancient passageways long-since lost to the people up above.


Tales of the Undercity

Some of the best urban myths about tunnels under Istanbul centre around the Ayasofya – or ‘Hagia Sophia’ – Mosque. Built in 537 AD, it originally served as the seat of the Patriarch of Constantinople; a Greek Orthodox cathedral. It was converted for the Roman Catholic faith in the 13th century, adapted for use as a mosque from the 15th century, and then secularised for a new life as a museum since 1935.

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According to the stories, there are tunnels beneath the Hagia Sophia that formed a network criss-crossing much of Constantinople. They once reached secret treasure vaults, and cisterns large enough to sail ships through; they connected to Topkapı Palace, and even, some say, reached as far as the Prince Islands out in the Sea of Marmara.

A recent documentary programme titled, Beneath the Hagia Sophia, followed divers as they explored submerged tunnels under the building. These divers found the graves of saints, dating as far back as the 13th century; passages that forked off beneath Sultanahmet Square and Topkapı Palace, allegedly constructed by Emperor Theodosius II in the 5th century to allow secret movement beneath the busy streets of his capital.

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The imperial residence at Topkapı Palace.

There was no sign, however, of tunnels beneath the Bosphorus – or of tunnels to the Prince Islands either, so named for their history of royal exiles as various heirs fought over the Sultan’s throne.

Although, there is one set of tunnels beneath Istanbul, even crossing beneath the Bosphorus Strait, that still receives an incredible amount of traffic nowadays: the metro.

Istanbul Metro represents a phenomenal engineering feat and after the London Underground, it is the second oldest underground rail system in the world; its first line, Tünel, opened in 1875.

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Byzantium-8-Metro 2The latest line added to the network is the 2013 Marmaray Tunnel, an undersea railway that stitches together the European and Asian continents.

During the construction of these sub-aquatic routes, from Yenikapı to Üsküdar, the project frequently ran into ancient remains. Wooden ships were found, buried in the silt layers at the bottom of the Bosphorus: Constantinople’s medieval port, complete with galleons, their cargos in many cases still intact.

The city has other tunnels though, which are not so deeply hidden; and from time to time I’ve had the chance to explore the forgotten architecture of Constantinople for myself.


The Ruins of Constantinople

In the 1950s, the archaeologist Rüstem Duyuran managed to uncover large portions of the Hippodrome of Constantinople. Later, in the 1980s, old buildings were cleared to reveal a surviving substructure of the Sphendone: the curved end of the hippodrome, which rises now in layers of crumbling brick around the back of the Sultan Ahmed Mosque.

Some of these spaces I have explored for myself; open archways in the stone, some sealed behind metal grates but others perfectly accessible for those prepared to climb up to them. By day, there is a near-constant stream of pigeons flying in and out of these ancient portals; at night, it’s bats. Largely, however, these visible entrances to the Sphendone culminate in dead-ends. The remains of staircases are sometimes visible inside, or doorways later bricked up, but more often than not these spaces lead to empty hollows – or nests of bottles and dirty blankets.

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After climbing into a few such holes in the ancient walls, the ruins of former Constantinople, I began to get the feeling that it had all been done before. The real treasures of Istanbul had long-since been removed, and the most interesting places secured against unwanted visitors… until at least, the Ministry of Culture could build a ticket booth and begin charging for entry. Indeed, there are even tunnels and cisterns beneath the Hagia Sophia that have been explored, documented by the city’s archaeologists – and then sealed up again, without ever being opened for the tourists.

Another time, I’d see more of those alluring entranceways set into age-old rock. We were setting out to find the tramrail that curves around the southern coast of Fatih district; along the Marmara coast, beneath the walls of Topkapı Palace. We pinpointed a station on the map – but reaching it, found a mass of tumbled bricks, overgrown tracks and an underpass barred in fences and keep-out signs.

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Opting instead to walk our intended route, we came through streets lined in abandoned houses, walls stained in graffiti and even, at one corner, the black and twisted shell of a burnt-out car. Hard to believe we were no more than a 10-minute walk from the city’s most lavish, tourist-friendly districts… it can sometimes be surprising how closely these worlds are squashed together, in Istanbul.

The street spilled out into a park. Along the back wall, arches and doorways rose from the grass – ancient pillars buried up to their waists in the lawn, structures that had stood for countless centuries as the ground level gradually rose around them.

Byzantium-9-Walls 2I was peering at one of these entrances, wondering how deep the passageways went; whether these were more dead-ends, bird nests and bricked-up tunnels, or, perhaps, an entrance to some invisible network beneath the earth.

As I watched, a pale shape emerged from the shadows. An old man, white skin and white beard, shuffled out of the darkness with a blanket slung across his shoulder.

Looking about the park then I saw others – drinking from plastic bottles, cooking food on campfires or watching me, quietly, from ancient archways or the shadows at the corners of the park. Some of these men looked content but others were gaunt, ragged, almost certainly homeless; and here they were, Istanbul’s most desperate citizens taking refuge in the ruins of the city’s former palaces.

In many ways, it seems futile to hope to find anything truly unseen in a city such as Istanbul. Officially it has a population of 14 million people – though locals will tell you that the true number is higher still. As attractive as it sounds in a place with such deeply layered physical history, Istanbul is the fifth most populous city in the world: so the chance of stumbling across some overlooked wonder here is virtually impossible. The secrets of Constantinople are mostly either lost, or locked up tight.

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But here, it is the synthesis of past and present that keeps me coming back. The sounds and lights projected through the hollow cisterns; the aqueducts that nimbly step across these busy highways; the millennia-old monuments that stand to attention above vendors selling hot chestnuts and selfie-sticks. The city might have deeper secrets still – but there is only so much they could add to a metropolis already built from stones laid thousands of years before.

I had experienced this synergy, even on my very first visit to the city. It was late October and walking along the waterfront, some way down from the palace on a road that wound about the very southeast tip of the European continent, I was watching the Turkish Republic Day fireworks. As the night sky filled with colourful bursts above, a stranger approached me from a path that cut inland.

He was young, perhaps 16, and seemed keen for a chance to practice his limited English. We spoke for a while before he offered to show me something: something wonderful, he said, as he waved back into the pitch-black parkland from where he’d come. It was an odd scenario – and possibly, unsafe – but I was curious, and so I followed.

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Past old stone walls he led me, tumbling, curved walls that looked more like barrows, along a narrow path that snaked through the rough ground beneath the palace walls. We reached a door in the wall, he opened it, and waved me on through ahead of him.

Stepping into the darkness and down a short flight of steps, it was the smell that hit me first. A musty, sweaty, grassy smell, and as the boy flicked on an electric light I found myself stood in a subterranean stable. The horses appeared well-bred: sleek, dark creatures that looked like racing stock.

I turned to find my guide stood behind me, wide-eyed with pride, as he stared along the curving passageway.

“Are these… your horses?” I asked, a little perplexed, and he waved his hands as if to correct me. It wasn’t the horses I was here to see, I realised. Instead, he motioned once again down the tunnel, the space between the walls, the bricks that curved off out of sight into the darkness.

“Byzantium,” the boy said, slapping the cool rocks. “Byzantium!”

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  1. I really enjoyed your post. I visited Istanbul bac k in 2005.I had some free time between my arranged tours and went exploring with my guidebook. I wanted to see the Bucoleon palace. I made my way along the sea wall as it faces the JFK highway. As I approached it I saw the large openings at the upper part of the sea wall that were pictured in the guidebook. I noticed in the sea wall there was an opening with a bush growing in front of it large enough for me to duck down and go inside. I felt like I was inside some sort of room. There were numerous white marble columns with a large cross on the 4 sides of the capitals. The wall across from the opening had collapsed and I was able to walk out the other side, I felt as if I was walking on a large concrete slab-roof that had fallen in. It was broken and seemed to be on multiple levels. On the opposite side appeared to be a ruined wall of a building. I’m wondering if I stumbled on “Justinian’s house” or the “Palace of Hormisdas”. Both of which I think were built up against the sea wall in the vicinity of the great palace. Do you have any thoughts as to what I might have been looking at?

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