This imposing, seaside complex in the Kalamaja district is now one of the best places in the world to catch a glimpse of Soviet-era prison life in all its dreariness. Originally opened as a sea fortress in 1840, it housed inmates from 1919 until 2004, and has been left virtually untouched since. Visitors can explore the hallways to see cells, work areas, exercise yards and the like. There are also several tours available see website for details.

Admission €2.