Römerturm

This guide to the Römerturm in Cologne examines the diamond and rosette mosaic of red sandstone, white limestone and grey trachyte on its curved face, raised around AD 50 as the northwest corner of the Roman colony's defensive wall. Of nineteen matching towers built into that ring, only this one still stands whole, and the guide traces the almost embarrassing reason why: Franciscan nuns who built their convent against it in the early 1300s and began using its dim interior as a latrine. It follows the tower's long slide toward possible demolition in the 1870s.