For 492 years (1420–1912), it served as China's royal residence. It has a total size of 0.72 square kilometers (0.28 square miles), with a floor area of 15 hectares (38 acres). It consists of 980 structures in over 70 palace complexes, totaling over 8,700 rooms. It is 961 meters long and 753 meters broad from south to north. The center section, which includes the emperor's living quarters, is larger than the other two sides combined. Built near Beijing between 1407 and 1421 for Emperor Yongle, the father of Emperor Xi, this magnificent palace complex is one of China's oldest surviving buildings. It was used by various members of the imperial family until 1912, when the last emperor moved into the palace. Today, the main parts of the complex are protected as an ancient monument by the government. Access is allowed only on pre-arranged tours that include a presentation about how modern technology has been used to preserve the site. The complex consists of three main sections: the east, west, and south courts. Each court is surrounded by high walls with more than 1000 openings through which soldiers could fire arrows at invaders (the people inside the palace would have had protection behind thick walls). Inside the walls are different types of buildings for lodging, storing goods, and making art. There are also several large ponds with islands in them; these were used for fishing and hunting. In addition to being a luxurious place to live in, the Chinese Palace was also a major scientific research facility.