Avalokitesvara ('Lord who looks down') is a bodhisattva who embodies the compassion of all Buddhas. He is one of the more widely revered bodhisattvas in mainstream Mahayana Buddhism. The Mogao Caves, or Mogao Grottoes (Chinese: mògao ku, also known as the Caves of the Thousand Buddhas and Dunhuang Caves) form a system of 492 temples 25 km (15.5 miles) southeast of the center of Dunhuang, an oasis strategically located at a religious and cultural crossroads on the Silk Road, in Gansu province, China. The caves contain some of the finest examples of Buddhist art spanning a period of 1,000 years. The first caves were dug out in 366 CE as places of Buddhist meditation and worship. The Mogao Caves are the best known of the Chinese Buddhist grottoes and, along with Longmen Grottoes and Yungang Grottoes, are one of the three famous ancient sculptural sites of China. The caves also have celebrated wall paintings.