The Forbidden City (Chinese: 紫禁城; pinyin: Zǐjìnchéng) is a palace complex in Dongcheng District, Beijing, China, at the center of the Imperial City of Beijing. It is surrounded by numerous opulent imperial gardens and temples including the 22-hectare (54-acre) Zhongshan Park, the sacrificial Imperial Ancestral Temple, the 69-hectare (171-acre) Beihai Park, and the 23-hectare (57-acre) Jingshan Park. The Forbidden City was constructed from 1406 to 1420, and was the former Chinese imperial palace and winter residence of the Emperor of China from the Ming dynasty (since the Yongle Emperor) to the end of the Qing dynasty, between 1420 and 1924. The Forbidden City served as the home of Chinese emperors and their households and was the ceremonial and political center of the Chinese government for over 500 years. Since 1925, the Forbidden City has been under the charge of the Palace Museum, whose extensive collection of artwork and artifacts were built upon the imperial collections of the Ming and Qing dynasties. The Forbidden City was declared a World Heritage Site in 1987. The complex consists of 980 buildings, encompassing 8,886 rooms and covering 720,000 square metres (72 hectares)/178 acres. The palace exemplifies the opulence of the residences of the Chinese emperor and the traditional Chinese palatial architecture, and has influenced cultural and architectural developments in East Asia and elsewhere. It is listed by UNESCO as the largest collection of preserved ancient wooden structures in the world. Since 2012, the Forbidden City has seen an average of 14 million visitors annually, and received more than 19 million visitors in 2019. In 2018, the Forbidden City's market value was estimated at US$70 billion, making it both the world's most valuable palace and the most valuable piece of real estate anywhere in the world. Some sources describe it as the largest palace in the world still in existence, but other Chinese imperial residences far exceed it in size, namely the 6.1 km2 (610 ha) Zhongnanhai which lies just west of the Forbidden City, the 2.9 km2 (290 ha) Summer Palace in Haidian District, Beijing, and the 5.6 km2 (560 ha) Chengde Mountain Resort in Chengde, Hebei Province. The Forbidden City in Beijing is one of the largest and most well-preserved ancient wooden structures in the world. It is a national AAAAA-level tourist attraction in China. It was listed as the first batch of national key cultural relics in 1961 and listed as a world cultural heritage in 1987.