To complicate nomenclature even further, Carcassonne's Ville Basse is usually referred to as La Bastide--'bastide' being the word for a fortified purpose-built market town with a large central square surrounded by a rectilinear grid of streets.
The settlement began to grow and prosper, so in 1250 a typical bastide town was built, with its grid of narrow streets surrounded and protected by a huge wall with only four entrances.
He didn't have enough men or supplies to capture Carcasssonne's citadel above the Aude, so he threatened to burn down the now thriving bastide. When La Bastide's residents 'offered the Prince the enormous sum of 250,000 ecus d'or in return for not setting fire to their town', he refused and burned it to the ground.
Carcassonne refused to help with the construction costs, so the canal's route was originally about a mile north of La Bastide. At the start of the nineteenth century Carcassonne realised that it was missing out on the commercial benefits of moving goods by canal, so it paid for a diversion to be built.