During almost half a century of the Soviet occupation, estimated 122.000 persons in Estonia fell victim for communist crimes against humanity. More than 30.000 of them lost their live. The Soviet security service NKVD/KGB had their central office for Southern Estonia in the so called Gray House in Tartu. KGB's jails were located in the basement of the Gray House, where the Tartu City Museum has an extension since October 2001. Some of the prison cells have been restored as they were during the Soviet era, others host the permanent exhibition of the KGB museum. The museum exposes the Soviet occupation of Estonia as well as resistance against the occupation.