Binnenalster or Inner Alster Lake's one of two artificial lakes within the city limits of Hamburg, Germany, which are formed by the river Alster (the other being the Außenalster). The main annual festival's the Alstervergnügen. The lake has an area of . History The phrase "inner" refers to the old city walls of Hamburg. The Binnenalster was the part of the lake that was "inside" the city walls. The lake was originally created to serve as a reservoir for a mill. As of 2008 the old city… (More on Binnenalster)