The second wall is a punishment. After Raymond Trencavel’s son failed to retake the city in 1240, Louis IX expelled the inhabitants, founded the grid-planned Bastide Saint-Louis across the river in 1247 and, with his son Philip III, threw a whole new enceinte outside the old one. The gap between the two is the lices, and it is a killing ground: an attacker who got over the outer wall found himself in a walled corridor overlooked from both sides with nowhere to form up. About 3 km of double wall and 52 towers survive. By the 19th century the lices were packed with houses; Viollet-le-Duc cleared them, which is the only reason you can walk here at all.
What to look at, from below. On the inner wall, the north and east stretches are Gallo-Roman at the base — late third to fourth century, small blocks banded with courses of red brick, semicircular towers, no machicolation. Beside and above that is bigger, squarer 12th- and 13th-century stone. On the outer wall the towers are lower, plainer and open at the back, because they were never meant to be lived in. Every pointed slate roof you can see is Viollet-le-Duc’s, from 1853 on. The flat tiled roofs he replaced are what a 13th-century garrison would have known.
The specific thing to find is the Tour de l’Évêque, on the west side above the Porte d’Aude. Built under Philip III (1270–85) in large bossed sandstone blocks, it is the only tower that spans the lices from wall to wall, sealing the passage between the upper and lower lices and covering the Aude gate and the castle behind it. Square, machicolated at the corners, it makes the logic of the whole system readable in a single object. At the south-west angle, the Tour du Grand Burlas holds the corner of the outer wall.
Go in through the Porte Narbonnaise on the east — twin towers on spurred bases, a drawbridge approach, and the stone bust called Dame Carcas at the outer gate — then take the ramp down beside it rather than following everyone up the main street.
