Building houses off the ground on stilts serve a number of purposes: it allows breezes to moderate the hot tropical temperatures; it elevates the dwelling above stormwater runoff and mud; it allows houses to be built on rivers and wetland margins; it keeps people, goods and food from dampness and moisture; lifts living quarters above malaria-carrying mosquitos; and reduces the risk of dry rot and termites. The sharply inclined roof allows the heavy tropical rain to quickly sheet off, and large overhanging eaves keep water out of the house and provide shade in the heat. In hot and humid low-lying coastal regions, homes can have many windows providing good cross-ventilation, whereas in cooler mountainous interior areas, homes often have a vast roof and few windows. Examples of "rumah adat" include: The numbers of "rumah adat" are decreasing across Indonesia. This trend dates from the colonial period, with the Dutch generally viewing traditional architecture as unhygienic, with big roofs that sheltered rats. Multi-family homes were viewed with suspicion by religious authorities, as were those aspects of the "rumah adat" linked to traditional belief. In parts of the Indies, colonial authorities embarked on vigorous demolition programmes, replacing traditional homes with houses built using Western construction techniques, such as bricks and corrugated iron roofs, fitting sanitary facilities and better ventilation. Traditional craftsmen were retrained in Western building techniques. Since independence, the Indonesian government has continued to promote the 'rumah sehat sederhana' ('simple healthy home') over the "rumah adat". Exposure to the market economy made the construction of labour-intensive "rumah adat", such as the Batak house, extremely expensive (previously villages would work together to construct new homes) to build and maintain. In addition, deforestation and population growth meant that the hardwoods were no longer a free resource to be gathered as needed from nearby forests, but instead a too-expensive commodity. Combined with a general appetite for modernity, the great majority of Indonesians now dwell in generic modern buildings rather than traditional "rumah adat". In areas with many tourists, such as the Tanah Toraja, "rumah adat" are preserved as a spectacle for tourists, their former residents living elsewhere, with design elements exaggerated to the point that these "rumah adat" are considerably less comfortable than the original designs. While in most areas "rumah adat" have been abandoned, in a few remote areas they are still current, and in other areas buildings in the style of the "rumah adat" are maintained for ceremonial purposes, as museums or for official buildings.