The Forbidden City was the Chinese imperial palace from the mid-Ming Dynasty to the end of the Qing Dynasty. It was built between 1406 and 1420 and consists of 980 surviving buildings and covers 720,000 square metres. It is built in traditional Chinese palatial architecture and has influenced the architectural developments in East Asia. The Forbidden City was declared a World Heritage Site in 1987, and is listed by UNESCO as the largest collection of preserved ancient wooden structures in the world. Since 1924 it houses a collection of artworks and artefacts open for the public. The Forbidden City is surrounded by a 7.9-metre high city wall and a six-metre deep, 52-metre wide moat. The walls are 8.62 metres wide at the base, tapering to 6.66 metres at the top.