Built in the late 9th century CE under Indravarman I, Wat Bakong is the largest temple in the Roluos group and said to be a representation of the sacred Hindu mountain Mt Maru. Standing at 15 metres tall, its five layers 60m square base, it had seen several expansions under later kings with the uppermost section and tower added as late as the 12th century. Some of the lintel carvings on the outer towers are still in good condition.