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 and operated as an artillery battery, it housed inmates from 1919 until 2002 and has been left virtually untouched since. Most of the year the prison is closed to visitors, but you can still see it from the outside. From May through September, The Estonian Institute of Historical Memory has opened an exhibition area 'Communism is Prison' which introduces the nature of communist ideology, its international crimes, stories of its victims, and the history of the complex. The museum and research centre will continue to expand in the coming years. Entrance to the area is from the side facing the Port of Tallinn from Suur-Patarei street through the gate, or from the seaside promenade through the small gate.