Klapperfeldstrasse
The Gestapo headquarters in Frankfurt was on Lindenstrasse 27, but their prison was about 800 meters further away on Klapperfeldstrasse.
Current status: Preserved with museum (2011).
Address: Klapperfeldstrasse 5, 603 13 Frankfurt am Main.
Get there: Metro to Konstablerwache Station.
Follow up in books: Höhne, Heinz: The Order of the Death’s Head: The story of Hitler’s SS (1969).
During my visit, I had the impression that parts of the prison are being used by alternative youth groups for various activities. I have no idea if any historical rooms still exists.