The area known today as Syria is one of the longest-inhabited parts of the globe. Since it was first settled between 2,500 and 2,400 BC, the region has been controlled by a diverse array of civilizations, including the Hittites, the Umayyads, the Greeks, the Romans, and the Byzantines. Its ancient cities of Palmyra and Damascus were once centers of trade connecting the Roman Empire with distant lands such as India and China.
Today, however, many of Syria's precious cultural heritage sites are under threat. The two-year-old civil war has already taken its toll on structures ranging from fortresses to temples. And the antiquities left after the fighting are often looted and swapped for weaons, according to Fernande van Tets's dispatch for Foreign Policy.
Here, we've collected images of some of the amazing ruins that have either been damaged or remain at risk as war rages around them. Many of these sites have yet to be fully explored; now that chance may never come.
The ancient city of Palmyra, pictured above, was once known as the "Bride of the Desert." People began living there in the Paleolithic era, but the city did not rise to prominence until the first century AD, when the Romans conquered it. Palmyra connected the Roman Empire with Persia, India, and China, and thus became a valued trading post and the most vital stop along the Romans' caravan route to the East. Today, it is surrounded by troops on both sides of the war, and its ruins have been damaged by everything from shrapnel to rockets to mortar rounds.