Preah Ko (The 鈥榮acred bull') was built by King Indravarman I (877-889); and was a Hindu temple dedicated to the worship of Shiva and constructed in memory of Indravarman's parents and an earlier king; Jayavarman II; the founder of Roluos.

The main sanctuary of Preah Ko consists of six brick towers set on a low laterite platform. Formerly each tower would have contained an image of a Hindu deity; but these have long since disappeared.