St Nicolas Tower
This slightly leaning tower (total height 42m) is a veritable fortress. It was built in the 14C and named after the patron saint of seafarers. An external staircase leads to the superb octagonal-shaped Salle des Gouverneurs which boasts an elegant rib-vaulted ceiling. There's a fine view of the harbour, the bay and Aix island from the upper platform in the watchtower, which is flanked by high walls with arrow slits and machicolations.