The Forbidden City is the world's largest surviving palace complex and covers 178 acres. It consists of 980 surviving buildings and was designed to be the center of the ancient walled city of Beijing. It is enclosed in a larger, walled area called the Imperial City. The Forbidden City's name referred to the fact that no one could enter or leave the palace without the emperor's permission. Construction began in 1406 of what would become the Forbidden City. Construction lasted 15 years, and required more than a million workers. After being the home of 24 emperors—fourteen of the Ming Dynasty and ten of the Qing Dynasty—the Forbidden City ceased being the political center of China in 1912. It is currently being resstored to its pre-1912 state.