In contrast to the kasba, the family unit is the ksar , which is mainly a collective grouping. Inside the defensive walls, which are reinforced by angle towers each with a zigzag-shaped gate, houses crowd together. Some are modest, others resemble small urban castles with their high angle towers whose upper portion presents decorative motifs in clay brick. But there are also buildings and community areas: collective sheep pens and stables, lofts and silos, market place, meeting room for the assembly of family chiefs, mosque, madrasas, etc.