The walls of Aigues Mortes were traced out by St Louis, but the superstructure was executed by his son, Philip the Bold. The latter in 1272 took possession of the country of Toulouse and arranged with the Genoese Boccanera to construct the walls of Aigues Mortes for a sum equal to 88,500 francs. The town is laid out as a regular parallelogram with streets at right angles, [Illustration: FIG. 117. AIGUES MORTES--WALLS ON EAST AND NORTH SIDES.] like the bastide of Carcassonne on the north side of the Aude. The walls are built with solid masonry, having the natural surface left rough or bossy. Fifteen towers surround the city and strengthen the curtains at the angles and on the flanks. There are nine gates, two principal ones, and the others smaller. Being only a fortification of the second order the defences of Aigues Mortes are not nearly of so complete a type as those of the important fortress of Carcassonne. The towers are generally round, though some of them, following the Southern fashion, are square and project only slightly (Fig. 117). The gateways pass directly through the square towers, which, as we have seen at Avignon, was a decidedly Southern custom; and none of the circular towers have strengthening beaks. The towers are so placed with reference to the walls that some of them, as at Carcassonne, interrupt the parapet walk, while in others it is carried round the outside of the inner face of the tower, and is supported on large mouldings which form a continuous corbelling. This is shewn in the view of one of the towers above a gateway taken from within the walls (Fig. 118). The stairs giving access to the walls and the interior of the loopholes are also seen in this view. The walls of the town, which are about 30 feet high, are all provided with a crenellated parapet, having long loops in the merlons between the embrasures. The wall heads have also been defended with wooden hoardings, the holes for the beams which carried them being very distinctly visible all round the fortress. The lower part of the wall is perforated with very long narrow slits. The interior recesses connected with these are formed with wide splays like window bays, and are provided with stone seats for the defenders (_see_ Fig. 118). Probably the great [Illustration: FIG. 118. INTERIOR OF SOUTH SIDE OF WALLS.] length of the loops was to enable bowmen to operate both while standing on the floor and on the seats, or even on temporary wooden platforms at different heights, and also to aim their arrows either high or low. The open staircases leading to the walls are carried up on the side next the town in the same way as those of Carcassonne.