The Washington Park Arboretum, more plainly known as the Seattle Arboretum, is located northeast of Downtown and south of the University of Washington, jutting out into Lake Washington. This is the last land the 520 floating bridge crosses, when travelling eastward. The Washington Park Arboretum has been Washington's official "State Aboretum" since 1923. Its land and buildings are owned by the City of Seattle. The University of Washington Botanical Gardens manages the plant collections, and Seattle Parks and Recreation manages the park's functions. The Arboretum covers approximately 230 acres.