The Imperial Palace, also known as the Forbidden City, was the imperial palace of emperors in the Ming and Qing Dynasties. Located at the centre of Beijing, it was built in the 4th year of the reign of Emperor Yongle (1406) in the Ming Dynasty, and completed 14 years later ( 1420) ; it boasts a history of more than 570 years. There were 14 emperors in the Ming Dynasty and 10 emperors in the Qing Dynasty who had been enthroned and ruled here. The Forbidden City, rectangular in shape and 720,000 square meters in size, owns 9,999 and a half rooms, the floor space of which is about 160,000 square meters. The palaces are surrounded by the purplish-red walls 3 ,400 meters long, and a moat 52 meters wide and 4.1 meters deep. At the middle of the four walls stands a gate tower respectively: the Meridian Gate in the south, the Godly Prowess Gate in the north, the Donghua Gate in the east and the Xihua Gate in the west, and at each of the four corners stands a tower. The whole Forbidden City looks like a strongly fortified castle. It is composed of two parts, the outer palace where the emperors held grand ceremonies, discussed state affairs with high-ranking officials and exercised their powers, and the inner palace where emperors conducted routine government affairs and empresses, concubines, princes, princesses resided, amused them- selves and worshipped gods. There are over 920, 000 pieces of valuable historical relics stored in the Imperial Palace. It is the largest and most complete ancient wooden architectural complex among the existing ones in China and in the world.