The Royal Palace was built on a site considered auspicious by King Norodom's royal astrologers and ministers; it is located opposite where the waters of the Upper Mekong, the Lower Mekong, the Basak and Tonle Sap rivers converge. It was built in 1866 during the French Protectorate (1847-1953) by the architect Neak Okhna Tepnimith Mak, and has been extensively modified and remodelled by subsequent monarchs. Most of the buildings in the Palace compound follow the layout of the buildings of Angkor, but incorporate both modern Khmer and Western design elements. In Khmer culture, the Palace functions on three levels: as the residence of the ruler, as a venue for court rituals and ceremonies, and as a symbol of the Kingdom. The Throne Hall was inaugurated by King Sisowath in 1919, and was used for coronations and other royal ceremonies.