Do you know how old the Palace Museum is? It is 600 years old this year! It was China’s imperial palace (皇宫) from 1420 to 1911. Twenty-four emperors once lived there. People called the Palace Museum the Forbidden City (紫禁城) at that time. It is the largest building complex (建筑群) of ancient palaces in the world. All palaces are built out of wood. Now it is open to tourists all over the world. Many foreign leaders visit the museum when they come to China.