The curtain wall which joins Bastions No. 6 and 7 was blown up during the liquidation of the fortress. At the turn of the 1970s and 1980s the section of the curtain wall between Bastion No. 7 and the postern was reconstructed. Originally, the curtain wall was an earth embankment faced with brick on the side of the moat. In the 19th century a firing gallery with a row of vertical embrasures was built inside the curtain wall. An Underground Tourist Route leads along the gallery. In front of the postern there are walls of the caponier with semicircular passages and longitudinal openings – remains of locks which regulated the level of water in the ditch. The caponier was used to defend the moat and supported an overpass which joined the postern to the opposite bank of the moat; it also joined the fortress to the area in front of it.
