Alte Lahnbrücke, Stone arch bridge in Wetzlar, Germany

The Alte Lahnbrücke is a 104-metre-long stone bridge with seven circular arches crossing the Lahn and the Lahninsel. Its roadway is cambered, dropping 1.90 metres toward the old town and 2.40 metres toward the suburb. The two outer arches span 7.40 and 8 metres, the middle ones 10 to 10.50 metres.

The Alte Lahnbrücke was probably built between 1250 and 1280 to replace a wooden bridge, making it one of the oldest surviving bridges in Hesse. The foundation chronicle of Altenberg Abbey names the priest Gottfried von Beselich as the initiator who collected alms for its construction. In the 15th century the piers were reinforced with cutwaters, and 17th-century town views show two tower structures, one a prison tower, demolished in 1832. The bridge was closed to motor traffic in 2011.

The bridge is named after the river Lahn and the nearby Lahninsel, the island it crosses. Since 2011 it has been closed to cars and is used only by pedestrians and cyclists, so crossing it today means sharing the deck with walkers and bike traffic between the old town and the Vorstadt.

Since 2011 the bridge has been closed to motor traffic and is reserved for pedestrians and cyclists. The roadway is cambered, dropping 1.90 m from its highest point toward the old town and 2.40 m toward the suburb, so the crossing is not level. The parapet is a concrete core faced with rubble stone.

In 1865 the original wall was replaced with an iron lattice structure to create a new walkway. This modification shows how the bridge adapted to the changing needs of the city over time.