From the outside, Chungking Mansions looks like a single, imposing concrete block - 15 identical residential floors on top of a neon-lit, two-storey mall.
Past the front, it is like a maze - there are in fact five separate blocks, 10 lifts and multiple old, twisting stairwells filled with swathes of electrical cable, crumbling concrete and graffiti in multiple languages.
The complex began life as an upmarket residential estate in the 1960s, but has since become a hub for traders from developing countries, backpackers and asylum seekers in Hong Kong.
More than 10,000 people are estimated to enter or exit the building every day, and African and South Asian faces often outnumber Chinese faces - something remarkable in a city where 94% of residents are ethnic Chinese.
The building complex has a somewhat notorious reputation among locals and, until recently, many in Hong Kong were wary of stepping inside.
However, the building has a buzz that most Hong Kong Chinese would also recognise - nearly everyone is there to make money.
'Low-end globalisation'
Entering the building, touts try to lure the visitor to their restaurant, or offer a hotel room.
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Chungking Mansions consists of 5 17-storey buildings
Across the first and second floors are shops selling clothes, computers and boxes of cheap electronics such as mobile phones. As well as selling to the public, the stalls cater to wholesalers who ship goods to Africa and South Asia.
Gordon Mathews, an anthropology professor at the Chinese University of Hong Kong who spent four years researching and staying in Chungking Mansions, describes the complex as "a world hub of low-end globalisation".
Traders from developing countries come to Chungking Mansions to buy goods in demand back home, he says, "carrying their goods in their own luggage, or renting a container or part of a container, and shipping the goods pretty much on their own".
The deals are done "on the basis of trust, and often under the radar of the law," he says.
Many traders try to avoid import taxes by carrying their merchandise themselves or bribing customs officials, while many of the employees in the shops are working illegally.
Prof Mathews estimates that in 2008, about 20% of mobile phones in use in sub-Saharan Africa had been sold in Chungking Mansions, although that number has since decreased.
Many of the phones sold today are 14-day phones: phones which were returned by European customers within 14 days of purchase, which retailers buy at a discount and sell on.
Directly above the phone shops, a very different kind of business is thriving.
The 15 storeys above the mall are packed with guest houses converted from the building's original residential apartments.
Numbers of visitors have soared in recent years, as relaxed border controls have led to an influx of tourists from mainland China.
Lam Wai-lung owns the Dragon Inn, one of the larger guest houses.
The smallest room has barely any space apart from the bed and costs HK$180 ($23; £15) a night, while the largest - the deluxe honeymoon suite - costs $700 ($90; £60) a night during peak season.
"A few years ago, 70% of my clients were from Japan," she said. "Now, around 70% of the customers are from mainland China, as they have become wealthy."
But China's opening up has also presented threats to businesses in the complex, as some mobile phone buyers now head to Guangzhou instead of Hong Kong, traders say.
Eddie Wong, a wholesale phone dealer from Hong Kong, said competition from China was fierce.
"Business isn't as busy as before. China has opened its markets and traders can apply for visas [to mainland China] very easily. Meanwhile, the Hong Kong government has tightened visa requirements for African customers, so most of them go to China now."
"Also, they can buy phones more cheaply in China."
Many traders were reluctant to be interviewed. Some were asylum seekers and illegal workers who could not risk being identified - while others were simply busy making money.
With its five separate blocks, winding staircases and constant flow of people, Chungking Mansions may seem like a good place for those who want to disappear off the radar.
But in fact, comprehensive CCTV coverage makes it nearly impossible to enter or exit the estate undetected. When I approached the management office for an interview, they said their security staff had noticed me hours ago, after my loitering drew their attention.
The first CCTV cameras were installed around 10 years ago in a bid to improve safety, security manager Matthew Tsoi said.
There are around 330 CCTV cameras now, covering around 70% of the building's public spaces.
The management office takes obvious pride in its CCTV system, and the role it has played in improving security.
Crimes still take place - the reported rape of a mainland tourist in June sparked headlines. But an arrest was made hours after the crime was reported to police, as officers used CCTV footage and door-to-door searches to apprehend the suspect.
"Most buildings in Hong Kong are quite homogenous, with mostly Cantonese people, so there aren't as many different cultural activities or living habits that need to be accommodated," he said.
Despite this, the different ethnic groups in Chungking Mansions appear to get on relatively well. "The world seems to become smaller in Chungking Mansions," dealer Eddie Wong said.
"Even though there are so many people from different races and religions, they all know what they're doing in Hong Kong... most have come here to make money. So that's why they will not have major conflicts - even Pakistanis and Indians are friends here."
"Chungking Mansions is seen as proof of Hong Kong's international nature. It's one reason why the place has become quite popular with locals."Hong Kongers want to see Hong Kong not as Chinese, but as increasingly international.
Source: BBC
