Südbrücke, Railway bridge in Mainz, Germany

Südbrücke is a railway bridge over the Rhine between Mainz and Ginsheim-Gustavsburg, carrying the Mainz–Frankfurt line at kilometre 496.4. Its four main spans use steel half-parabola trusses with a 104.96 m span, and a footbridge on the north side lets pedestrians and cyclists cross. The bridge begins between two surviving neo-Gothic towers on the Mainz bank.

The Südbrücke was built between 1859 and 1862 to plans by Heinrich Gerber of the Klett ironworks in Nuremberg, replacing a train ferry between Mainz and Gustavsburg. It was Mainz's first permanent Rhine bridge and Germany's fourth railway bridge over the river. Its wrought-iron Pauli trusses were replaced in 1911 by steel half-parabola girders; the neo-Gothic towers on the Mainz bank survive from the original structure.

The bridge is part of German railway heritage and shows the connection between Mainz and the industrial areas across the Rhine. It shapes the landscape of this region as a distinctive steel structure.

A foot and cycle path is mounted on the north side of the bridge structure, so pedestrians and cyclists can cross the Rhine here. The bridge stands just above the mouth of the Main, between Mainz Römisches Theater station and Mainz-Gustavsburg station. On the Mainz bank the path begins between the two surviving neo-Gothic bridge towers.

The bridge never received an official name, so it has been called Südbrücke, Eisenbahnbrücke Mainz-Süd and Mainz-Gustavsburger Eisenbahnbrücke. Its neo-Gothic towers on the Mainz bank were purely decorative, meant to screen the unfamiliar iron construction from view, and had no military function; the architect was probably Justus Kramer.