Every layer of this city needs preserving

The drama of Mardin's position is best appreciated from the air.

The city clings to the southern flank of the last escarpment of the Taurus Mountains, facing the vast plains of Mesopotamia. From above, a neat line is visible marking the last convulsions of the massif – mushroom and mud tinted – beyond which a sea of green takes possession of the Earth's crust. This is the cartoon geography of a semi-mythical place; Mesopotamia, the land between the rivers Euphrates and Tigris, aka The Cradle of Civilisation. But it wasn't just myths that were created here. It was history.

The current official version would like to paint Mardin in the United Colours of Benetton – as a multi-ethnic, multi-faith, multi-cultural playground of bright-eyed co-residents, where Kurds, Syriac Catholics, Mahalemi Arabs, Orthodox Armenians and Turks all rub along happily, under one flag. But in this layer cake of a city, each layer tells a story. Some layers are invisible; they are an absence. People who should be here are not here – their former homes have been put to new uses, their places of worship neglected and ruined. History happened here. History scared them into leaving.

In Istanbul, 700 miles away, they were surprised that I was going to Mardin. An artist I met said no, she had never visited. "There are a lot of military there, you will see," she said pointedly. Others were more blunt and suggested the region is dangerous. In a shocking incident less than a year ago, 44 villagers in Mardin municipality were murdered at a wedding. The authorities were keen to play it down as Kurdish intra-clan violence but the details of who did what and why remain murky.

It looks peaceful enough. There is an army base to one side of the road from the provincial airport. Behind the base, rocks have been rolled together to form large words on the hillside. Translated they say something like "Happy to be Turkish". They do protest too much. As recently as the Eighties and Nineties the Turkish army was putting down the Kurdish insurgency in this region with "extreme prejudice". The Syriac population was caught in the crossfire. Memories are also long enough to remember the genocide of Armenians and Syriacs perpetrated by the Ottoman Turks and Kurds back in 1915. It's complicated.

The Syriac population of the town is down to a meagre 1 or 2 per cent – many relocated to Sweden. There are maybe six or seven Armenian families left, the last Jews upped sticks in the early 1980s. Even the Kurds, though still the majority, have suffered a diaspora as far flung as Canada.

There are, however, reasons to be cheerful, according to Mesut Alp, a local historian. "My parents' generation thought of themselves as Kurdish first, Muslim second and human third," he tries to explain. "But for me it's different, my generation thinks we are human first." We're picking our way through the veg market and through the minefield of regional politics. Mesut is saying the aspiration for a Kurdish nation state is no longer so important for him in a world where national boundaries are being broken down; joining the larger human family of the EU is the priority.

A cockerel, bred for fighting, struts across the pavement, pausing to fluff its chest and flap its wings in display. We pass a gun shop with hunting rifles lined up in the window. They are carved and engraved with intricate patterns – objects of desire. Next door is a bank with a hole-in-the-wall cash dispenser, followed by a string of shops selling mobile phones. A heavily laden donkey, part of the municipal refuse collection service, clatters past in the narrow, cobbled street. It is hard to settle on which century these street vignettes belong to.

Modern Mardin, if that isn't an oxymoron, is a celebration of architectural misrule. It tumbles down from a hilltop fortress, oblivious to planning. For more than six millennia it has bent to the will of successive masters and they have left their marks in stone and, more recently, concrete. Churches, mosques, minarets, monasteries, villas, bazaars, bus stations and flat blocks elbow each other for space. But the defining features of the city are terraces.

The terrace of the Antik Tatlidede Hotel explains why the architects of Mardin favoured this feature. The hotel, built in the late 19th century, was once home to a prosperous Syriac merchant. The view is enormous, dizzying, Biblical. We are perched on a cliff, and the land falls away to an ocean. Despite the absence of spray and surf it is hard to shake off the illusion. Down there the fertile plains rise to meet a flat horizon over a hundred miles deep inside Syria.

It has been Mardin's mixed fortune to be on the Silk Route – making it a magnet for traders and tyrants alike. Marco Polo stopped here on his way to China in the 13th century – a more benign visitor than Tamerlane, who laid siege to the city (unsuccessfully) a century later. The Abdullatif mosque, built just a few years before the Mongol emperor arrived, is a testament to the city's ability to absorb and endure. The outer portal is finely carved and looks in remarkably good nick – which is perhaps not surprising because it was added less than 10 years ago. The minaret was also an addition (19th century) but the mosque is greater than the kit of parts assembled over seven centuries.

More sweeping terraces characterise the Mardin Museum, which was once the home of the Syriac Catholic patriarch. It is a graceful affair with four or five levels supported on rounded arches and rows of faux-classical pillars linked by grand balustraded staircases. It is another of the town's many theatrical buildings that cry out for performance – perhaps grand opera or a sword-and-sandal epic.

This is Mesut's workplace and he can't conceal a note of pride when he shows off some of the exhibits. Pointing to a child's toy that resembles a stone tractor, he says he found it in a local villager's home. It was still being used as a plaything by the kids who had dug it up in the family plot. The "tractor" is at least 5,000 years old.

The view from the museum's grandstand is untidy. The main square below is presided over, predictably, by a heroic statue of Mustafa Kemal Ataturk, father of the Turkish Republic. He stands at the top of a wedding-cake monument exhorting citizens to put "country before everything". On the far side of the square, the view is interrupted by multi-storey concrete blocks sprouting satellite dishes and cables. Mesut talks enthusiastically of an EU-backed project to rid the city centre of the unsightly concrete and show Mardin in all its honey-coloured limestone splendour to eagerly awaited hordes of tourists.

"I'm a bit suspicious about the idea of turning Mardin into a museum city," says Clemens von Wedermeyer, a Berlin based video-artist who is in the town for another EU (and British Council) sponsored project. The idea is to bring established artists from Europe to five cities in Turkey to create major works of public art. Turkish artists will go the other way, on residencies. It is an attempt to build cultural bridges in tandem with the country's bid to join the EU.

But Clemens is perhaps a bit off-message. "I am an anti-museum, anti-institutional artist," he says. "I think it's more interesting to encounter the dynamics of the city and if you control that from the top and turn it into a museum – then only tourists will inhabit the space."

Clemens' installation won't be a museum piece. "Addressing the complexity of this area – the ethnicities, religions, different cultures – I thought of an empty square, 10 to 12 metres wide, that looks like a cinema screen, something like the monolith in 2001 (Stanley Kubrick's film), a screen of desires where you can project your fantasies. And that reflects for me some of the psychology here, which has often to do with unfulfilled desires."

Clemens wants his installation, which is due to be unveiled later this year, to be a device for cultural dialogue within Mardin's disparate communities. "It's like a mirror. Where you can see yourself and where you can see the others, your neighbours."

Later, I am woken by the muezzin's call to prayer. It is 4.20am and the sound is loud enough to pierce sleep. He has an exquisite voice. He recites the adhan, rising through the register in fractions of notes, hitting the highest with avian clarity, then retreating down the scale in resolution. In my dreaming consciousness, it no longer matters who is doing the singing or why. The voice seems loaded with the yearning of all peoples, when history is done, for peace.

Compact Facts

How to get there

Sankha Guha travelled to Mardin as a guest of the British Council. Turkish Airlines (thy.com) flies to Mardin via Istanbul from £495. Double rooms at the Antik Tatlidede Hotel (tatlidede .com.tr) cost from €80 per night.