Beihai Park (Beihai Park), located in the central area of Beijing, on the west side of the city, on the northwest side of the Forbidden City, is jointly called the Three Seas with the Zhonghai and South China Sea. It belongs to the ancient Chinese royal garden. The whole park is centered on the Beihai, with an area of about 71 hectares, with 583 mu of water and 480 mu of land. It was originally a palace of Liao, Jin, Yuan Jianli, Ming and Qing Dynasty, and was the imperial palace. It is one of the oldest, most complete, most comprehensive and representative royal gardens in China. It was opened as a park in 1925. The oldest and most complete royal gardens preserved in China are national key cultural relics protection units and are national AAAA-level tourist attractions.