Willemstad is a small historical town with well preserved and moat in the shape of a star (see google image below).
Another oldie being given city rights in 1585, and still very small but perfectly in character retaining its charm and beauty. Again, pre the 1953 flooding it was open to the sea (hence the heavy fortifications dating back to war and viking times). As well as the fortifications and the moat it also had the required Dutch windmill and a great town quay wall which we were able to berth at right in the centre of the town (which was great until they started pulling up and relaying the pavers throwing dust all over us!).