The bastion has a triangular plan with rounded corners. Its sides are about 25 metres long and its present height is about 12 metres. At the corners there are three towers, each containing a round room covered by a corbelled dome (B, C, D). One reaches the two rooms at the corners of the main facade (B and C) directly from the main entrance through two passages opened on the left and right side of the corridor. Room B is oval (base 4 x 5 m; height 7 m). Room C is circular (base diameter 4 m) and its dome is partially collapsed. Room D (base diameter 4 m; height 8 m) is at the back of the building and has a small independent raised entrance; it is connected to the top of the bastion by a steep staircase. The top terrace of the bastion could be reached from the upper room of the central tower by another staircase.
