Wat Phu Khao Thong, (About 3 km north of town, west off the Ang Thong Rd). Impressive and huge white, and slightly wonky, chedi set in a big field. You can climb to the top for extensive views over the countryside surrounding Ayutthaya, although the modern town and power lines obscure much of the historic city on the horizon. The actual nearby temple is still working and has small grounds with a smiling fat buddha image set in the ruins of a small viharn. You will see the 'Monument of King Naresuan the Great' on the way. Free.
