In most villages everyone builds (designs, builds, decorates, does maintenance, etc…) and everyone knows the construction process. Traditionally, men build the walls and roofs. Women, during the exterior construction, bring water, and later do the finishing-work such as interior surfaces. Families and neighbors all help each other, knowing that when it comes time for them to build, they will get help in return. In some cases, a builder from another village may come to supervise construction, and in still other cases there are specially trained masons belonging to guilds that hold trade secrets. These famed groups usually handle construction of major buildings like mosques.