Angkor was the site of a series of capital cities of the Khmer empire for much of the period from the 9th century to the 15th century CE. Their ruins (13°24'N, 103°51'E) are located amid forests and farmland to the north of the Great Lake (Tonle Sap), near modern day Siem Reap, Cambodia, and are a UNESCO World Heritage Site. The temples of the Angkor area number over one thousand, ranging in scale from nondescript piles of brick rubble scattered through rice fields to the magnificent Angkor Wat, said to be the world's largest single religious monument.