Ancient Hariharalaya, the capital of Indarvarman I (9C), used to house several of the so-called "Roluos Group" (in reference to the nearby modern town) temples. Preah Ko, the king's ancestral temple, Bakong, his main temple, and Lolei, in the heart of the water reservoir, heralded the beginnings of classic Khmer art. With both Preah Ko and Lolei facing east, it is in the morning that you will enjoy the best light. Bakong is a great viewpoint from which to admire the sunrise.