Villages are built on shelves several hundred feet above the Hunza River gorge (approximately 2,500 to 3,000 meters above sea level) and are heavily fortified. Access to individual villages in this area is obtained by traveling on narrow roads that are also located high above the river basin. Homes are never built on arable land. Construction materials consist of stone, rock, or clay. Doors, roofs, supporting pillars, and a few other household features are made of wood. The lower floor of a home has two sections: a courtyard (uncovered) for animals; and a living space for human use. Homes are built in close proximity to one another and are in a sense located almost on top of one another.