In the north-west corner of Beijing, in an area renowned as a base for huge technology companies, stands a non-descript building a few stories high.
Inside, in a small set of modest offices, is the hub of something quite extraordinary - a club that counts billionaires amongst its members.
"There's little else like it anywhere else in the world," says leadership expert Steve Tappin, who is the presenter of the BBC TV documentary China's Billionaires' Club.
"It's very hard to imagine the top 50 CEOs in America or Europe happily getting together or going on foreign trips as a group," he adds.
The China Entrepreneur Club consists of 46 of China's top business leaders. They are joined by politicians, academics and other advisers.
Several of the members are billionaires. They include Guo Guangchang, who's been described as China's answer to Warren Buffett, property tycoon Wang Jianlin, and Jack Ma of e-commerce giant Alibaba, who's believed to have recently overtaken Mr Wang as China's richest man.
The club offers a forum where company founders can meet and share ideas, and offer advice to each other.
Since it was formed in 2006, the organisation has held regular events, some on a large scale. CEC members have also travelled the world together, meeting presidents and prime ministers keen to learn more about China's business elite.
The club is extremely difficult to join, and new members are rarely admitted. Amongst other attributes, candidates need to have an exemplary track record of business success, and must share the club's values.
Given that entrepreneurs are often extremely competitive people, how could a club like this possibly work? The answer, according to Charles Chao, chief executive of giant internet firm Sina, is that the members come from different industries, so they are not competing with one another.
"It's an honour just to belong to this organisation," adds Mr Chao.
Members also rally round each other when one of them encounters difficulties. Mr Chao says the level of support available "is beyond my expectation." He sees it as a key benefit of membership.
So how did it all come about? The answer partly lies in the uncertain status of the business community in China.
"Society sometimes mistreats entrepreneurs, and has a lot of misconceptions about them," says the club's founder, Liu Donghua, who used to publish a magazine aimed at people who have launched businesses.
Mr Liu says that one of the main reasons he started the club was to promote greater acceptance and understanding of the private sector.
Today, even though China may now be an economic juggernaut, the events of the past still cast a long shadow.
For decades under Communist leader Mao Tse Tung, the state controlled the economy. The private sector disappeared almost completely.
The violent and chaotic Cultural Revolution of the 1960s and 70s damaged the social fabric, and trust between people was often lacking. This would have made doing business very difficult, even if it had been possible.
So when the Chinese government began to open up the economy in the 1980s, the first wave of entrepreneurs found the going tough. They were often greeted with suspicion.
"There's an old saying in our culture - there are no merchants or business people that are not cunning or sly," says Joe Baolin Zhou, chief executive of Bond Education. "I still remember in the 1970s and 80s a lot of intelligent people would feel ashamed of becoming a business person."
In addition to dealing with discouraging social attitudes, business pioneers faced many other difficulties too.
Liu Chuanzhi is founder of huge computer company Lenovo, and is also chairman of the China Entrepreneur Club. He says state-backed enterprises were often given special privileges (such as favourable access to foreign currency), which made it difficult for start-ups like his to compete.
But even once the trailblazers of China Entrepreneur Club and others like them had achieved a level of success, some had doubts about how long it would last.
"Chinese entrepreneurs survived unique circumstances like government intervention, and the idea that 'the state advances as the private sector retreats,'" says CEC member and billionaire Huang Nubo. "Entrepreneurs in the private sector in China live a difficult life. They need to fight against huge market uncertainty."
Social attitudes remain a challenge too.
"Successful entrepreneurs in China have an image problem," says Kent Deng, reader in economic history at the London School of Economics. He believes that business leaders need to become more involved in charitable work, to help change how they are perceived.
Some Chinese company bosses are now becoming philanthropists, with CEC member Huang Nubo being just one of a number of wealthy entrepreneurs who have made substantial charitable donations.
But will it be enough to persuade an often sceptical Chinese public to be more welcoming of the business community?
CEC chairman Liu Chuanzhi says the club has a role to play: "We believe private companies of a certain magnitude, like ours, have the responsibility and obligation to help enable the private sector enjoy healthier development in China".
Like most prominent Chinese business leaders, CEC members are reluctant to talk about or get involved in politics. Nevertheless some members say they can see business leaders and organisations like the club playing a wider role in society.
Deng Feng, founder of Northern Light Venture Capital, says he and some other CEC members have sponsored a private think tank, to look at social and environmental issues such as what can be done about the problem of pollution.
"It's going in the right direction" he says.
Club members say they get value from belonging to the organisation. But Huang Nubo warns that there are limits.
Mr Huang has a large tank in his office, with a shark in it. He says there were originally three sharks - but the remaining one killed the other two.
"It's not impossible for entrepreneurs to cooperate, but this requires great skills," he says.
A documentary about the China Entrepreneur Club and the recent history of business in China will be broadcast on BBC World News channel on 25th October at 09:30 and 21:30 and 26th October at 02:30 and 15:30. It will also be broadcast on the BBC News channel on 25th October at 16:30 and 26th October at 01:30 and 10:30. All times are GMT.