The Saint-Blaise tower is the last vestige of the Commandery that the Knights Templar built during the twelfth century, beneath the town ramparts, at the side of the road leading out from the Saint-Paul gates towards the salt marshes. This thoroughfare gradually became the main axis of the lower town. The tower comprises two storeys and contains a chapel and a room above, both with barrel vaults. A staircase built inside one of the walls leads up to the fortified terrace.