The whole reason to come to Sukhothai is the Sukhothai Historical Park — the moated ruined capital, declared a UNESCO World Heritage Site in 1991 along with its sister cities Si Satchanalai and Kamphaeng Phet. Within the central walled enclosure are the most important temples: Wat Mahathat, the former royal temple at the heart of the city; Wat Si Chum, with its colossal seated Buddha framed by a narrow doorway; the perfectly composed Wat Sa Si on its island in a lotus pond; Wat Sri Sawai, built on earlier Khmer foundations; the hilltop Wat Saphan Hin with its standing Buddha; and Wat Phra Phai Luang in the northern zone. The Ramkhamhaeng National Museum by the central gate is the essential starting point. Sixty kilometres north, Si Satchanalai is quieter and equally rewarding, with the spectacular Wat Chang Lom. The ancient hydraulic engineering of the Saritphong Dam closes off the valley to the west.