Dionysius had rebuilt the walls around Ortygia so that they surrounded the whole island and the isthmus connecting the mainland with a robust wall complete with towers at regular intervals which were strongly built. The isthmus had docks on the west side and the little harbour, Laccius on the east side. Screens and walls were put up to enclose Laccius, and it could accommodate 60 triremes, and a gate was provided between the sea screens that would let one trireme pass at a time. Two castles were also built on Ortygia, one near the isthmus, which was the home of Dionysius, and one further south. Two walls were built on the isthmus itself, one separating the island from the isthmus and one the mainland from the isthmus. A series of five gates built on the isthmus, the "Pentaplya", controlled access between the mainland and Ortygia.