It is now home to around one million poor migrants who have moved to Beijing to realize their dreams

By the 90s, the government started leasing out the tiny subterranean units as cheap apartments

Strategy was abandoned when Deng Xiaoping took over, hundreds of squatters took over the shelters

Chairman Mao built network of 20,000 bunkers under Beijing fearing Soviet Union attack in 1969


They moved to the city with dreams of making it big.

But for countryside-bred migrants, life in Beijing is not cheap.

The answer? Go underground.

Welcome to the so-called Rat Tribe: the one million people that have made a home out of bunkers below the surface of China's second-biggest city.

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The Rat Tribe: Niu Song, 33, and his wife Zhao Ansheng, 32, are both chefs who live under Beijing to save money - like hundreds of others

The history: The structures were erected in 1969 under Chairman Mao's rule during the Cold War who feared an imminent Soviet attack

With some as low as 300 yuan a month ($48), they are a fraction of the price of rentals above ground.

The structures were erected in 1969 under Chairman Mao's rule during the Cold War.

Fearing an imminent Soviet attack, cities were ordered to prepare safety measures. Around 20,000 bomb shelters were dug.

When Mao died and Deng Xiaoping came to the fore, such defensive tactics were sidelined - leaving the city with a pointless network of caves.

Unsurprisingly, hundreds of entrepreneurial landlords descended on the bunkers, letting out rooms as hostels.

By the mid-90s, the government latched on to the scheme and many of the rooms are now part of a for-profit housing system.

An alternative: Twenty-five-year-old Ji Lanlan and her three-year-old daughter, Yu Qi, enjoy a game on their computer in one of the largest rooms in this basement in west Beijing, China. The units were built in 1969 under Chairman Mao who feared a Soviet Attack

Bar waitress Jiang Ying, 24, and 23-year-old office worker Li Ying have lived here for one and a half years to avoid sky-high rental prices

When Mao died and Deng Xiaoping came to the fore, such defensive tactics were sidelined - leaving the city with a pointless network of caves

Located near the deserts of the north east, the network is also a welcome environment for all seasons: cool in summer, warm in winter

It means people like Zhang Xi, an aspiring actor from Mongolia, can support themselves and pursue their dreams.

His parents implored him to take a job as a policeman back at home where he could be comfortable. But he is determined.

In a short film by artist Sim Chi Yin that explores the subterranean network, he explained: 'When my father came to visit me he cried when he saw where I lived. He said, "Son, this won’t do."'

'But I told him: "When I go out and meet people I always look very presentable. Who's going to be able to tell that I live in a basement?"'

Other dwellers include Chen Laxiu, a 50-year-old woman from the coal-mining town of Liupanshui, who moved to Beijing to be near her sons after farming proved unprofitable.

Making ends meet: He Bing, 23, tries on a borrowed suit and tie for size the night before an examination to become an insurance salesman

Melon seeds and instant noodles are splattered all over the floor in his room, but Liu Fei, 24 in purple, originally from Anhui Province, is just having a smoke and playing a computer game. For him, all the matters is making ends meet in Beijing, China's second-biggest city

Uncertain future? A question mark hangs over their future as officials in 2010 announced a crackdown on health and safety in the city

Zhang Xinwen moved to the bunkers after graduating from high school in Hubei province to pursue a career as an artist.

Li Yang, from Beijing suburb Tongzhou, wants to be a fly fishing official, but currently works as a car mechanic, and lives in the bunkers to save money.

And an entire family - Xu Junping, her 17-year-old son Zhou Zhengdi, and her husband Zhou Hailin - have opted for a simpler life.

Located near the deserts of the north east, the underground network is also a welcome environment for all seasons: cool in summer, warm in winter.

Though most of the inhabitants foresee a move on to bigger and better things - above ground - the vast majority are content and grateful.

Xie Jinghui, originally from Jiangxi, used to live in a more central location within Beijing's 3rd Ring Road, but one year ago the house was torn down. He says: 'Everybody thinks that living in the basement is only a temporary thing but then people end up staying much longer'

Something of a family home for this couple: Shang Lanlan, 27, and her husband have moved underground for lack of funds. They have left their 5-year-old son with her parents back in their native Shandong Province in eastern China

However, a question mark hangs over their future as officials in 2010 announced a crackdown on health and safety in the city.

And the native citizens see the Rat Tribe as unwelcome intruders.

But despite city plans to wipe out the system by 2012, it provides a convenient answer to the question of affordable housing.