The Oberbaumbrücke in Berlin stand today as a symbol for the city. The first version at the location was made out of wood and was built in 1732. The name is derived form the German word for tree, and refers to the location being upstream from the big tree trunk that was used to close the river where the old city wall was. At that location, a Baum was put over the river, so ships could not pass.
At the end of the 19th century, the wooden bridge was replaced by this stone neo-gothic structure. It was created so the metro could pass over the river, along with pedestrian traffic and horse drawn coaches. It was badly damaged in the Second World War, and stayed that way until the Wende, when the Berlin Wall fell. During the time of the Berlin Wall it happened to be between the American and Russian sectors, so there really was no incentive to renovate it.
I write this, because the bridge functioned as a border crossing between East and West at the time this string quartet was performing. The Kreuzberger Quartet were a string quartet from this area in Berlin.