Having passed an outer gateway in a 20 meters high tower a bridge brings one to the next or inner gateway. Inside it one is lead through complicated corridors with defence options all the way to the courtyard of the citadel. First consisting of two towers it has been added to repeatedly in 1260, 1290-3 (a long inscription), 1415 (upper facade and deep arch connecting the towers) and in the 15th and 16th century.