Ponte Schlösser de Erfurt

Originally built next to a ford as a wooden bridge over the Gera, the castle bridge was first mentioned in the 13th century as a long bridge between the castle mill and the new mill.The construction of the first stone bridge followed after the town fire of 1736. However, this was a mixed construction, consisting of two vaults on both banks and a three-span wooden bridge in between. During a renovation in 1862, the middle part was replaced by three more stone vaults and the bridge was widened to 10 m. The bridge axis was buckled.During World War II, an air raid on November 26, 1944 destroyed the neighboring buildings, such as the New Mill and the Reibstein department store, and severely damaged the Castle Bridge. The castle mill, which had not functioned since 1937, was removed in 1944 as a precautionary measure because of its flammability in fear of fire bomb attacks. As part of the repairs to the Castle Bridge, the building was modified by 1949. This included straightening and widening on both sides to 18.4 m, for which purpose the alignment of the new mill was withdrawn. Concrete was used to extend the vaults. In addition, the previously seven-span bridge was shortened by demolishing an arch and correspondingly shifting the eastern bank wall.Due to damage to the old natural stone vaults, four arches were finally replaced by concrete vaults in 1965 and the two western vaults at the new mill were demolished and filled. Since then, the Schlösserbrücke has had four water-bearing culverts, three of which are visible on the south side and one is covered by the New Mill. The two filled openings can also be seen under the current.Source: Wikipedia

The Schlösserbrücke is located in the Schlösserstraße in Erfurt and leads over the Breitstrom, a branch of the Gera. During the Second World War the bridge was badly damaged and later rebuilt and reinforced. Today there is even a tram over it. Many day trippers and lovers immortalize their love with a lock and thus live up to the name of the bridge.

You certainly can't go through it by boat.