Bang Pa-In Royal Palace; also known as the Summer Palace; is a palace complex formerly used by the Thai kings. It lies beside the Chao Phraya River in Bang Pa-In district; Ayutthaya Province.

King Prasat Thong constructed the original complex in 1632; but it fell into disuse and became overgrown in the late 18th and early 19th centuries; until King Mongkut began to restore the site in the mid-19th century. Most of the present buildings were constructed between 1872 and 1889 by King Chulalongkorn.