As well known for its resident monkeys as its looming towers, this is Lopburi's most famous attraction. The three linked towers were built from laterite and sandstone by the Khmer in the 13th century as a Mahayana Buddhist temple. It was converted to Theravada Buddhism by King Narai in the 17th century (there may have been a period of Shiva worship in between). Two ruined, headless Buddha images are inside; a third, more complete Buddha sits photogenically in front of the central tower.
Visitors can enter through a heavy metal door that keeps the monkeys out. The monkeys here are especially playful and while many people enjoy it, you can also borrow a stick from the ticket office to keep them away.
This is one of the combined ticket sites.