The first inventory of the ruins was done in 1901 by the French geographer Etienne Aymonier. They were put under governmental protection by announcement in the Government Gazette, Volume 53, section 34, from September 27, 1936. Most of the restorations were done from 1964 to 1969 as a joint Thai-French project. The historical park, now managed by the Fine Arts Department, was officially opened by Princess Maha Chakri Sirindhorn on April 12, 1989.