WUHAN, Dec. 22 -- Central China's mega-city Wuhan has started the construction of the country's largest "underground city," as more cities look to underground space as land resources become scarce.

The city, capital of Hubei province, has entrusted U.S. architecture and interior design planning firm Skidmore, Owings and Merrill LLP (SOM) to design the underground complex, the urban construction authority said on Tuesday.

According to the blueprint, the complex will cost an estimated 8 billion yuan (1.2 billion U.S. dollars). It will have three floors with a total construction space measuring 516,000 square meters, equivalent to 72 soccer fields.

The underground section is scheduled to be completed in 2018 and will be connected to a ground structure and urban transport systems, including four metro lines. It is designed with commercial walkways lined with stores, cinemas, fitness clubs and other entertainment facilities.

The complex has been named "Optical Valley Central City" after China's biggest photoelectron information industry base in the city known as Optical Valley.

Jian Jianyong, deputy head of the project's management committee, said "Optical Valley Central City" is being built in a new district in the southeast part of the city, which is expected to improve the city's urban capacity, land use efficiency and reduce traffic congestion.