This is not the greatest photo but these walls are quite old, maybe hundreds of years old. In the distance beyond the walls you can see one of the main cell block buildings. During the Communist Czechoslovakia, the Communist government used the prison for holding and "liquidating" political prisoners, particularly in the 1950s. The conditions were harsh for prisoners. From what I hear the conditions are only slightly improved.
For the past 8 months I have had a pen-pal relationship with a Slovak prisoner in this facility. He made a request to the Sk organization, which I have been doing prison ministry with, for a native English speaker who would agree to a letter writing relationship.