Beijing is at the heart of the most highly populated nation on Earth. The city has been China's capital since 1406 when the Ming dynasty Emperor Yongle used the city as a northern base against the encroaching Mongols. He was responsible for building the imposing Forbidden City 14 years later, made world famous by Bertolucci's film, The Last Emperor. The entire empire was ruled from these 200 acres of palaces and temples until the 1911 Chinese Revolution. Beijing's modern buildings are equally impressive, such as the Great Hall of the People and Mao's Mausoleum, built in 1976.