The design of most houses throughout the world depends on the climate. People living in hot countries need their houses to be as cool as possible, while people in cold countries need their houses to be warm. The materials that people use to build their houses usually depend on what they can find around them. Stone, mud1, straw and wood are all natural materials that have been used to build houses for thousands of years. However, many modern houses are built from manmade materials such as steel and glass.

　　The ancient Greeks built their houses from sun-dried mud bricks laid on stone. The roofs were covered with pottery tiles2. Rooms were built around an open yard so that cool air could build up and move through the rooms during hot days.

　　Between 1000 A.D. and 1500 A.D., castles were built in Britain, France, Germany and many other European countries. Castles were built by important people such as kings and queens. They were not only great houses that the owners could show off to their friends, but also military3 bases with which the lands around them were defended.

　　The Incas built their homes from large rocks from the nearby mountains. The rocks were fitted together and the thick walls protected them against the cold wind in winter.

　　The Etruscans lived in western Italy around 2,500 years ago. Wealthy Etruscan families built luxurious4 palaces with beautiful bronze statues and mirrors.

　　The Iroquois people lived in the forests of North America. They built their long-houses using wood covered with sheets of thick bark5. These houses were huge, and several families lived in each one.