Lopburi is the capital city of Lopburi Province in Thailand. It is located about 150 km north-east of Bangkok. As of 2006 it has a population of 26,500. The town (thesaban mueang) covers the whole tambon Tha Hin and parts of Thale Chup Son of Mueang Lopburi district, a total area of 6.85 km².

The city has a long history, dating back into the Dvaravati period more than 1000 years ago, when it was known as Lavo. When the Khmer empire incorporated it, they destroyed all former buildings, so that the oldest ruins that can now be found in Lopburi are Khmer temples. It later became part of the Thai kingdoms and, during the reign of King Narai the Great of the Ayutthaya kingdom in the middle of the 17th century, Lopburi even served as the second capital, with a second summer palace, King Narai's Palace. The king stayed here for about eight months a year.

Today the city is most famous for the hundreds of Crab-Eating Macaques (Macaca fascicularis) that live in the middle of the city, especially around the Khmer temple, Prang Sam Yot, and a Khmer shrine, Sarn Phra Karn. They are fed by the local people, especially during the Monkey Festival in November. Because they are not afraid of humans, they steal whatever food they can find from unwary diners.

Prang Sam Yot, originally a Hindu shrine, has three prangs that represent Brahma, Vishnu, and Shiva (the Hindu trinity). It was later converted to a Buddhist shrine.