Schellenturm

The Schellenturm stands as a heavy, circular stone shell at the edge of the old city wall. It served as a fourteenth-century prison tower where the city kept debtors and common criminals behind walls several feet thick. In fifteen forty-six, a prisoner named Hans von Ulm supposedly escaped his cell by loosening a mortar stone, crawling through the gap, and lowering himself with a makeshift rope. The city council eventually converted the space into a residential tower for the poor.