BEIJING, April 18 (Xinhua) -- The Palace Museum, also known as the Forbidden City, will build a new underground warehouse to protect relics in a controlled environment with custom humidity and temperature settings, according to Shan Jixiang, curator of the museum.

Shan said that the new warehouse, which covers 8,285 square meters, will be equipped with better waterproofing measures for ancient art as well as special cases to protect relics from earthquakes.

The museum already has two underground warehouses for items.

The first one was built between 1987 and 1991, covering 4,818 square meters, and the second one was finished in 1997 with 15,970 square meters. However, due to outdated technology, items in the two warehouses are all stored at the same temperature and humidity settings.

The two warehouses are home to about 970,000 relics, while an additional 800,000-plus items are housed in buildings above ground.

The Forbidden City is expected to complete the construction of the new storage area in 2020 when it celebrates its 600th anniversary. An underground passage will also be built to connect the warehouses.

Home to the royal court between 1420 and 1912, the Forbidden City now houses more than 1.8 million collections of cultural relics.