iolani palace is a building in downtown honolulu, hawaii, united states. it was a palace for the kings and queens of hawaii. it is the only palace in the united states that was used as an official residence by a reigning monarch. two monarchs governed from iolani palace. they were king kalākaua and queen liliuokalani. after hawaii stopped having kings and queens in 1893, the building was used as the state's capitol building until 1969.