The phrase "outer" refers to the former Wallanlagen (city walls) of Hamburg. The Außenalster was the part of the lake that was "outside" the city walls, built in 1625. In 1804 city wall and ramparts were stripped down and re-naturalized to parks, but the spatial division between the two lakes was retained. Today, two car and rail bridges, the Lombardsbrücke and the Kennedybrücke, span the river at this location. The areas around the Außenalster developed slightly different on the eastern and western sides; while the western side became a wealthy suburban area around the late 18th century, much of the eastern side used to be a property of the finance department of the City of Hamburg and only developed in the later decades of the 19th century.