The Betsileo live in hamlets, which surround villages. From north to south, the major administrative centers are Ambositra (northern Betsileo), Ambohimahasoa and Fianarantsoa (central Betsileo), and Ambalavao (southern Betsileo). Smaller towns, also with administrative and market functions, stand between these small cities and the village level. There is no standard size for Betsileo villages, which range from seventy-five to several hundred inhabitants. The usual rural settlement pattern is one of villages and hamlets located on high ground above valleys where rice is cultivated. Streams and rivers flow through these valleys, providing water and alluvial soils from rainy-season flooding, and, once canals have been constructed, water for irrigation of many of the rice fields. There is often a striking visual contrast between the bareness of a village, the houses and red ground of which stand out in the absence of trees, and the vivid colors of the vegetation below—the rice in the valleys and terraces and the secondary crops growing between the village and the rice fields. More rarely, settlements are located high in the hills above or below elaborate spring-fed rice terraces. Even more mountainous sites, atop massive granitic outcrops, were occupied in the past for purposes of defense.