Dani compounds are scattered across the floor of the Grand Valley. The basic compound is one round men's house, a smaller round women's house, a rectangular common cook house, and a rectangular pig sty. The largest compounds may have up to half a dozen more women's houses. The structures are linked together by fences and open onto a common courtyard. Behind the houses, and enclosed by an outer fence, are casual household gardens. The houses are built of wood and thatched with grass. Compounds vary greatly in size. They may contain just a single nuclear family or many families and assorted others. A compound may stand by itself or it may be physically attached to several other compounds. The compound itself is a social unit, at least in terms of intensity of social interaction. These largest compound clusters may house well over 100 people, but they do not form social units. The population of the compound is fairly unstable, as people often move about from one place to another, usually in the same general area, for a variety of reasons. Although a few Dani now live at the government centers in houses with sawnlumber walls and corrugated-zinc roofs, most settlements in the Grand Valley have changed little in forty years.