Ongi was once one of the biggest Buddhist monasteries in Mongolia. The ruins are located 18km to the south of Saikhan Ovoo soum, Dund-Gobi province. The monastery consisted of 28 temples built on the two sides of Ongi River. The southern complex (11 buildings) was called Bari Lama temple and the northern one (18 buildings) was called Khutagt Lama temple. It is believed that Ongi had four big academies where math, meditation, philosophy and medicine were taught. From 1760 to early 1800, the monastery grew to a huge center housing over 1000 monks. Unfortunately, the whole monastery complex was severely destroyed during the communist purge in 1939. A large number of ruins can be seen in this area. The first temple after the destruction was built in 2004. There is a small museum in a ger featuring findings from the old times.