Preah Ko (the sacred bull).  Three bull statues of sandstone located in the front of and facing the temple's central towers) is located at Roluos between Bakong and Lolei. It is mid-way between Bakong and the road. It was built in late ninth century (879) by the King Indravarman I, dedicated to hindu Siva  funerary temple built for the king's parents, maternal grandparents, and a previous king, Jayavarman II and his wife.

Preah Ko consists of six brick towers arranged in two rows of three towers each perched on a sandstone platform. The towers face east, and the front central tower is the tallest. The sanctuaries are dedicated to three divinized forefathers of Indravarman and their respective wives. The front central tower is dedicated to Jayavarman II, the founder of the Khmer empire. The tower to the left is dedicated to Prithivindreshvara, King Indravarman's father; the tower to the right to Rudreshvara, his grandfather. The three rear towers are dedicated to the wives of these three men.The central towers all bear images of the Hindu god Shiva.