Bastide
When bastides were founded most had no city walls or fortifications. This was because it was a peaceful time in history. Such things were added later. This was done either through a special tax, or through a law that required that the people of the city helped build the walls. A good example is Libourne. Ten years after the city was founded, the people asked for money to build city walls. Once they had received the money, they spent it on making their city prettier, rather than building walls.