Cittadella
How Was Cittadella Built
The circuit is an ellipse rather than a square or a polygon, which is unusual and deliberate: on flat ground with no feature to anchor to, a curve gives the shortest wall for the area enclosed and no weak corners.
The construction is brick over a stone base, about 14 metres high and topped by a continuous walkway with a crenellated parapet. Thirty-two towers project at intervals to allow flanking fire along the face, and the whole is surrounded by a wet moat.
The four gates face the towns they were built to watch: Porta Bassano north, Porta Padova south, Porta Treviso east, Porta Vicenza west. Porta Bassano is the largest, with the Casa del Capitano and its sixteenth-century frescoes attached.
The walls were never given the angled bastions that gunpowder demanded elsewhere in the fifteenth and sixteenth centuries -- Venice fortified Treviso and Verona instead. That obsolescence is precisely why they survive as a medieval circuit rather than a modernised one.