The al-Burj Ayyubid fortress at the harbour.
From another websitre I quote: "On the eastern side, facing the mainland, a smaller, square Ayyubid Arab castle, dating from the late 12th century, overlooks the two natural harbor areas that, side by side, once hosted naval fleets, but now are filled with fishing boats, yachts and the ferries that ply to and from the mainland."