The Roluos Group is a collection of monuments representing the remains of Hariharalaya, the first major capital of the Angkorian era Khmer Empire. Setting the pattern for the next four centuries, the first great Khmer temples (Bakong, Preah Ko, Lolei) and baray (reservoir) were constructed at Hariharalaya.

Includes:

1) PREAH KO - one of the first major temples of the empire at the early Khmer capital of Hariharalaya. Preah Ko (Sacred Bull) derives its name from the statues of bulls at the front of the central towers. Many of the carvings are in very good condition providing excellent examples of the deep, vivid Preah Ko style Khmer art.

2) BAKONG - the most impressive member of the Roluos Group, sitting at the center of the first Khmer capital, Hariharalaya. Bakong represents the first application of the temple-mountain architectural formula on a grand scale and set the architectural tone for the next 400 years. The temple displays a very early use of stone rather than brick. Some of the lintel carvings, particularly on the outer towers, are in very good shape.

3) LOLEI - an island-temple consisting of four brick towers on a double laterite platform. The last major temple built at Roluos before Yasovarman I moved the capital to the Angkor area. Though the towers are in poor condition, there are some good lintel carvings, which display the distinctively detailed Pre Ko style. An active pagoda has been built amongst the ruins.