King Narai's Palace was built in the 17th century, when Lopburi served as a second capital and a stage for foreign envoys. The compound mixes surviving walls, royal halls, and later restorations in a shady enclosure west of the main temple ruins.
The Somdet Phra Narai Museum inside gives useful context for Lopburi's Dvaravati, Khmer, Ayutthaya, and royal periods. It is the right stop when the monkey temples begin to feel too chaotic.