Aerial view of the ruins of the ancient city of Hatra, located approximately 290 km (180 mi) northwest of Baghdad. Hatra was a strongly fortified caravan city and capital of the small Kingdom of Hatra, located between the Parthian and Roman Empires. Hatra flourished during the 2nd century A.D., but was destroyed and deserted in the 3rd century. Its impressive ruins were discovered in the 19th century. Photo courtesy of the US Department of Defense / Sgt. 1st Class Wendy Butts.