The National Museum in Surin is relatively small but it has an excellent collection of Khmer artifacts and is certainly worth visiting. There are some well-preserved sema (boundary) stones and architectural ornaments outside the main building in a covered walkway. The History-Archeology section has artifacts ranging from the prehistoric era to the Dvaravati Khmer and Ayutthaya-Lan Xang periods. Although it doesn't have nearly as many lintels as the museum in Nakhon Ratchasima the ones it does have are in excellent condition, including some from Prasat Sikhoraphum. It also has some striking torsos and Ganesh statues. Like most museums in Thailand it's open Wednesday through Sunday, 9AM to 4PM. There's no admission fee.
Surin National Museum