Sukhothai

This former capital and World Heritage Site had its heyday in the 13th and 14th centuries, leaving a rich legacy of ruins and temples.
Ancient RuinsThis 13th century capital is now a huge historical park and World Heritage Site. The remains of the old city are scattered within and around its ancient walls, betraying the golden era the city is now synonymous with. The classic religious art and architecture of the Sukhothai period have never lost their influence on Thai culture, and many later temples have emulated this style.
Temple TouringThere is an entry fee for each of the park’s five zones, and you can explore the old city by tram or bullock cart. Alternatively, hire a bicycle from shops near the park entrance, or rent motorcycles from guesthouses in the new city, 12 km to the east. The park’s hundred-or-so sites are mostly temples; here are some of those inside the walls:
The Ramkhamhaeng National Museum houses a copy of this famous king’s stone inscription, declaring the graces and freedoms of the city and its people. It is worth looking around here before seeing the sites. Walled, with a moat, the 13th C Wat Mahathat was the city’s biggest temple. It has nearly 200 stupas and still retains some of its original Buddha statues. The 12th C Hindu / Khmer-style Wat Sri Sawai has three prangs (towers) and is one of the oldest structures in Sukhothai. Other impressive ruins, both inside and outside the city walls, are Wat Sa Sri, Wat Trapang Thong, Wat Sri Chum and Wat Chang Lom.
Historical ParkAnother historical park, Si Satchanalai, is roughly 55 km from Sukhothai. The ruins date from the 13th to 15th centuries and are generally less restored and visited than those at Sukhothai, although no less inspiring. One of the many impressive sites, also named Wat Chang Lom, was completed in 1291. Stucco elephants flank its Sri Lankan-style stupa.
Reference :://http://www.circleofasia.com/Sukhothai-Thailand.htm