The bridge Oberbaumbrücke, built from 1894 to 1896, spans the Spree River between the city districts of Kreuzberg and Friedrichshain. This restored bridge has been an important link for automobile and U-Bahn traffic since 9 November 1994. From 1961 to 1989 it was a border checkpoint and could be used only by pedestrians.
On Mühlenstrasse, northwest of the former border crossing, a section of the inner wall painted in 1990 has been preserved between the Oberbaumbrücke and the Ost-Bahnhof train station. Known as the “East Side Gallery,” it is protected as a historical monument and was painstakingly restored in 2009 for the 20th anniversary of the fall of the Wall.
Five-year-old Cetin Mert drowned on 11 May 1975 at Gröbenufer, the bank of the Spree southwest of the Oberbaumbrücke. He had fallen from the high quay wall into the river, the entire width of which was on East Berlin territory. West Berliners and West Berlin firefighters rushed to the riverbank, but GDR border guards refused to let them rescue the boy.
West Berliners did not intervene, because they could have been shot for “violating the border.” The GDR border guards also failed to help. It was not until 29 October 1975 that the West Berlin Senate and the GDR government signed a treaty allowing West Berliners to respond to water emergencies along the border. In addition, Gröbenufer was secured by a fine-mesh fence and warning signs in several languages.
Correspondence between the two sides (only in German) can be seen at:”:http://www.chronik-der-mauer.de/index.php/chronik/1975/”:http://www.chronik-der-mauer.de/index.php/chronik/1975/