Frankenturm, Romanesque defense tower in Trier, Germany

Frankenturm is a fortified residential tower on Dietrichstraße near Trier's Hauptmarkt, built around 1100. Its base and corner quoins are large antique blocks taken from Roman buildings, and the upper storeys are faced with limestone hand-cut blocks interspersed with double courses of Roman brick. A semi-circular stone from a 2nd-century tomb, inscribed upside down, serves as a door lintel.

Built around 1100 and first documented in 1298, the tower was originally five storeys high and served ministeriales of the archbishop as a residential tower at the centre of a curtis. In 1308 it was reduced to two and a half storeys and given a lean-to roof. The upper floors were reconstructed in 1938/39 under city conservator Friedrich Kutzbach, with a crenellated wall instead of the top full storey.

The tower's name comes from Franco von Senheim, a 14th-century resident. It served ministeriales, officials in the service of the archbishop, as a residential tower and was the centre of a curtis with a large economic yard; a caminata novis is recorded in 1330. Today it is the starting point for the Tourist Information's experience tours and can be rented for events and conferences.

The tower is accessible from street level and often hosts public events throughout the year. Visitors should check ahead for specific visiting conditions, since the space primarily serves as an event venue rather than a traditional museum.

The eastern wall contains an upside-down Roman tombstone used as a stone lintel above a doorway, revealing medieval building practices. This detail shows how builders creatively reused fragments from the ancient city to construct new structures.