Brückturm, Medieval tower at Stone Bridge in Regensburg, Germany

The Brückturm is a five-story stone tower with a square base and pyramidal roof located at the southern end of the Stone Bridge in Regensburg. Inside, two modest rooms and a kitchen remain from when the tower keeper lived here, and visitors can explore these spaces today.

The tower dates only approximately to between the mid-13th and mid-14th century, when Regensburg's city walls were built; 2009 excavations suggest it replaced an earlier gate further south. With the Middle Tower and the Black Tower at the north end, it controlled access between the Stone Bridge and the old town. In the Thirty Years' War, Swedish defenders held it against imperial-Bavarian troops until a gunpowder shortage forced their surrender, leaving the tower badly damaged.

The tower's nickname, Schuldturm (debtors' tower), comes from its use as a prison for debtors, who could lower a hook from a tower window to beg for coins. On the north facade, a crowned king with a falconer's glove stands between King Philip of Swabia and Irene of Byzantium; these are copies of figures from the destroyed Black Tower, returned to the city in 1835.

The tower stands at the southern end of the Stone Bridge, where the bridge meets the old town. The top floor, once the tower keeper's two rooms and kitchen, is open as a viewing level with a view over the bridge toward Stadtamhof. Inside, a section of the Danube Shipping Museum is housed in the tower.

In peacetime the tower served as a Schuldturm, a debtors' prison, where inmates could let down a hook from the tower window to beg for a coin or two — recovering their debts in the literal sense. It is the only one of the three gate towers of the Stone Bridge still standing.