Although almost every building at this large temple complex across from the train station dates from the Ayuthaya era; the 31m-tall prang (Khmer-style spire) at its heart was built by the Khmer in the late 13th century and it's still the tallest in Lopburi. It's a beautiful structure built mostly of laterite and stucco. The temple is one of the combined ticket sites.
Many of the surrounding buildings are also in good condition including one particularly unusual stupa with U-Thong-style angles (their oblong faces and unusual halos are rare) in the northwest corner.