We tread carefully, as if tiptoeing around the scene of a crime, through a series of beautiful arches into the narrow alleys of the ancient Souk al-Medina, which at some eight miles long is one of the most glorious covered markets in the entire Middle East, selling everything from soap and spices to jewelry, shoes, ceramics and textiles. Merchants from Europe and China and Iran, from Iraq and Egypt, have met here in Aleppo, Syria, to sell their wares since the 13th century. For just as long travelers have immersed themselves in the ornamented Turkish baths, or hammam. The last time I ambled around the market, five years ago, I could barely move amid the bustle.

Now it’s an empty wasteland, and a war zone. The entrails of old buildings—tangles of concrete and metal corsetry—poke down from ceilings or hang limply out of their sides. Many have been broken by mortars or toasted into blackened husks by the fires that followed. Some of the old stone arches we pass through look about to collapse. Holes have been blown in the wall of an old mosque, and its dome has crumbled like deflated pastry. In over an hour walking the length of the market, the only nonmilitary inhabitants I see are two roosters, stepping in single file and picking carefully through the broken glass. Apart from mortar shells thumping to the ground elsewhere in the Old City and the occasional round of gunfire, there is little sound but the lurch and creak of steel and upended masonry, like sinister wind chimes.

The souk is within the walls of Aleppo’s historic city center, one of six locations in Syria listed as World Heritage Sites by Unesco. Before largely peaceful protests in 2011 against the autocratic Syrian president Bashar al-Assad were met with government violence and devolved into a devastating civil war, killing at least a quarter of a million people and displacing millions so far, the country was one of the most beautiful on earth. Much of its enchantment came from its plentiful antiquity, which wasn’t fenced off as in European capitals but lay unceremoniously around—part of the living, breathing texture of everyday life. The country, at the crossroads of Europe, Africa and Asia, boasts tens of thousands of sites of archaeological interest, from the ruins of our earliest civilizations to Crusader-era fortifications and wonders of Islamic worship and art.

Now these antiquities are under large-scale and imminent threat. Already some of the most valuable have been destroyed as collateral damage in the shelling and crossfire between government forces and various rebel factions; others have been sold off, bit by valuable bit, to buy guns or, just as likely, food or a way to escape the chaos. Satellite images of treasured historical sites show the soil so completely pocked by holes, the result of thousands of illicit excavations, that it resembles the surface of the moon—destruction and looting, as Unesco director general Irina Bokova put it last fall, on “an industrial scale.”