The Forbidden City, also known as the Palace Museum, was home to 24 emperors of the Ming and Qing Dynasties. The construction of the grand palace started in the fourth year of Emperor Yongle of the Ming Dynasty (1406) and ended in 1420. In ancient times, the emperors claimed to be the sons of heaven and therefore their supreme power was conferred upon them from heaven. Their residence on the earth was built as a replica of the Purple Palace where God lived in the Heaven. Such a divine place was certainly forbidden to the ordinary people and this is why the Forbidden City is so called. The museum is a real treasures house of Chinese cultural and historical relics, recognized as one of the most important five palaces in the world. The splendid architecture of the Forbidden City represents the essence and culmination of traditional Chinese architectural accomplishment. In 1961 the Forbidden City was listed as one of the most important historical monuments under special preservation by the Chinese central government and in 1987, it was nominated as a World Cultural Heritage Site by UNESCO.
The Forbidden City covers an area of about 150, 000 square meters. All the gates, palaces and other structures of the Forbidden City were arranged on both sides of the south-north central axis. The City falls into two parts: the outer court and the inner palace. The outer court is made up of three main buildings (Tai He Dian, or the Hall of Supreme Harmony, Zhong He Dian, or the Hall of Middle Harmony and Bao He Dian or the Hall of Preserving Harmony) where the emperors attended grand ceremonies and conducted state affairs. The inner palace is composed of the rear three main structures of the City, that is, Qian Qing Gong (the Palace of Heavenly Purity), Jiao Tai Dian (the Palace of Union and Peace) and Kun Ning Gong (the Palace of Earthly Tranquility). Furthermore, there are the six eastern palaces and six western palaces, where the emperor used to handle everyday affairs and which was the living quarters for the emperor and his concubines.
For security the Forbidden City is enclosed by a 10 meter high city wall, which has a circumference of 3, 430 meters. At each corner of the rectangular Forbidden City, there stands a magnificent watchtower, which was heavily guarded in the past. And around the outskirts of the City a moat goes as the last piece of defense.