Heidelberg's medieval city wall has almost entirely disappeared. The Hexenturm, or Witches' Tower, is the exception: a red sandstone tower that now stands in the New University's courtyard. It began as part of the town's defences, long before anyone planned a lecture hall.

The name points to a darker job. The tower reportedly held people accused of witchcraft. Then its protected status saved it again. When the New University went up, the architects built around the tower instead of knocking it down.

VoiceMap's self-guided audio tour of Historic Heidelberg stops here to explain how a wall tower became part of a university, funded in part by American donors, including John D. Rockefeller.