Prasat Phra Viharn is one of the most beautiful ruins of antiquity. Situated at a majestic height on the Dongrek Mountain Range, which marks the frontier between Cambodia and south-east Thailand, it is a Khmer shrine built between the 11th and 13th centuries. A series of sanctuaries and flights of stone stairways leads up the mountain to the temple tower, the centre of the worship of the god Siอa, to whom the shrine was dedicated. The extensive ruins, older than Angkor Wat, are evocatively preserved; roofs and columns have fallen, but the great native stone walls remain, and the massive carvings have been only softened and mellowed by the centuries.