Germany occupied Athens in late April 1941, and in the wake of the occupation, german secret police, Gestapo, arrived and set up headquarters at Merlin 6 in central Athens. Greek citizens suspected of anti-german acitivities were brought to the headquarter. There they were interrogated and the use of brute force was often used to extort confessions or concessions. Sometimes prisoners were released, sometimes they were sent to other prisons or camps. When the Germans retreated from Athens in October 1944, the headquarters reverted to civilian use.
Current status: Partly preserved/demolished with monument (2019).
Address: Merlin 6, 106 71 Aten.
Get there: Metro to Syntagma station.
Follow up in books: Höhne, Heinz: The Order of the Death’s Head: The story of Hitler’s SS (1969).
During the eighties, the building was converted into a shopping centre and no rooms or cells remain. To what extent these remained until then, I do not know. However, a cell door was found/preserved which is now part of the monument at the shopping centre entrance.