Gedenkstätte Berlin-Hohenschönhausen

This sprawling former remand prison run by the Stasi was used to incarcerate political prisoners - anyone from the leaders of the 1953 workers' uprising to critical students. You can visit only as part of a guided tour by ex-prisoners; these take 90 minutes. The experience is gut-wrenchingly bleak, but a potent insight into how the Stasi really operated.