ʻIolani Palace In USA

ʻIolani Palace, in the capitol district of downtown Honolulu in the U.S. state of Hawaiʻi, is the only royal palace now a part of the United States. It was used as an official residence of the reigning Hawaiian sovereign and is now a National Historic Landmark listed on the National Register of Historic Places. Two monarchs governed from ʻIolani Palace: King Kalākaua and Queen Liliʻuokalani, although Kamehameha III, IV, V, and William Charles Lunalilo had their main residences here as well. After the monarchy was overthrown in 1893, the building was used as the capitol building for the Provisional Government, Republic, Territory, and State of Hawaiʻi until 1969. The palace was restored and opened to the public as a museum in 1978.
http://en.wikipedia.org/wiki/'Iolani_Palace