The so-called key to Bremen connects the two shoresides of the Lesum for more than 600 years. The bridge, seeming to most Bremen citizens today rather mundane, has already written a whole piece of history. In 1350, there was at this point already the first wooden bridge.

It had been built by the Bremen archbishop and the city of Bremen-mostly for trading purposes. It used to be the only connection between the inner city of Bremen and the Northern part of town. At this point, the river Lesum is especially narrow and therefore suitable for a crossing. For this reason, the bridge, and the castle belonging to it , was an important standpoint that needed to be defended.

At the same time, the bridge was also a border area. Goods were transferred and duties collected.

For the area north of the Lesum belongs to the city of Bremen since 1939 only.

The bridge has often been destroyed by attacks or averse weather conditions, age or bad condition of the bridge only seldom brought on renovations.
In 1945, the bridge was destroyed by enemy attacks shortly before the end of the Second World War.

From 1950 to 2011, the steel bridge connected both sides. This bridge is now under renovation since 2011, because material samples revealed that it is unable to hold out the requirements for articulated lorries and heavy goods transport. The by now 12.

Lesum bridge was completed in 2013. It is 70 metres long and 17 metres wide and weighs 550 tons.