Si Satchanalai Historical Park
Si Satchanalai was founded in 1250 as the second city of the Sukhothai Kingdom. The city thrived until it was destroyed during the second Burmese-Siamese War of 1765-67. It was then abandoned, with the population relocating to Sawankalok. Restoration led to the historical park opening in 1988 and later designation as a World Heritage Site. Many sections of the old city walls are still intact, with the main sights easy enough to cycle and walk around.
Quite difficult to get your vertical composition right with all the leaning stupas and chedis.