Could you survive in the most crowded place on Earth?

Today the most overcrowded place on the planet is Manila, the capital of the Philippines, where the population density is estimated to be 107,560 per square mile. But it doesn’t hold a candle to the most densely packed place of all time, Kowloon Walled City, where between 33,000 and 50,000 people lived in a space of just 6.4 acres. That’s just 0.01 square miles, or less than five football fields in size.

Though the walled city is now just a memory preserved in post-apocalyptic photos and a few scant minutes of video footage, it remains an archetype for lawless urban dystopias. Unowned, ungoverned, ruled by gangs and avoided by police, surviving in the most crowded place on Earth, which was described by South China Morning Post as “a fetid slum, crawling with rats and dripping with sewage,” was no easy feat.

Kowloon Walled City has a strange history. What was once a simple trading outpost later became a Chinese military fort that, unlike the surrounding area, was not ceded to the British in the 99-year lease of Hong Kong following China’s defeat in the First Sino-Japanese War. When political refugees from China began pouring into Hong Kong starting in the 1950s, the fort ballooned into more than 300 towering buildings that were physically distinct but interconnected thanks to complex, unplanned construction cycles. The walled city eventually stopped expanding when the urban behemoth reached 500 structures.

According to Arch Daily, “The British [allowed] the Chinese to stay at the site as long as they did not politically interfere. China went on to fully reclaim the ownership of the Kowloon site in 1947, but its separation from the mainland meant they did little to enforce laws, while Britain also went with a ‘hands-off’ policy. Free from both sides of the law, squatters soon flooded in, and so began the legend of the Kowloon Walled City.”

How packed was it?

As the 99% Invisible podcast explains it, you’d have to cram the entire population of Texas into Manhattan in order to achieve the same population density. That’s 268,818 square miles worth of people jammed into just 22 square miles, or, in the case of Kowloon Walled City, nine people for every 1,200 square feet — though the average person had only 40 square feet to call their own, thanks to the numerous industrial workshops and commercial facilities that were also housed in the walled city. You can see for yourself how tight a fit it would be on the MapFight site.

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In the early 1990s, the government of Hong Kong evicted the tens of thousands of residents, then spent more than a year demolishing the site. In April 1994, Kowloon Walled City had been completely wiped off the map.

Could you survive in Kowloon Walled City, a place without running water or plumbing, swarming with brothels and gambling dens, and nearly no natural light and air? Possibly, if you followed seven rules.

1. Join a gang

With no oversight by either the British or Chinese governments, no police presence, and no landlords, Kowloon Walled City should have descended into anarchy. Instead, the triads took over. These organized crime syndicates were extremely powerful in Hong Kong at the time, with multiple branches such as the 14K and the Sun Yee On, which comprised tens of thousands of members.

In lieu of traditional rent, residents paid protection money to the triads, which further profited by setting up gambling dens, drug safe houses, and brothels within the walled city. If you wanted to thrive rather than just survive — especially if you were engaging in any sort illegal activities — your best bet was to get in good with the gangs.

2. Don’t get hooked on drugs

Drug use was rife within the walled city. As former resident Tang Kam-cheung told the Wall Street Journal, “The rich would take the ‘red pill.’ The second most expensive was opium. Opium-takers looked down on heroin users because it was the cheapest, but also the most toxic.”

Once you were addicted, there were few, if any, resources to help you get off the drugs. Better to avoid them at all costs.

3. Try to stay dry

The first camera crew to gain access to the walled city found a multitude of apartments linked by “subterranean corridors, the walls of which are dripping with water continuously … water that often breaks through the wall in cascades.” The result was a damp, unsanitary environment that, coupled with the lack of modern plumbing and a sewer system that consisted solely of open drains, was ripe for the spread of disease. As one resident of two decades put it, “It is very unhealthy here. My room is always wet. … For many, it would be better if they got out of here, but most are here for generations.”

4. Avoid the live wires

Though neither the British nor the Chinese governments provided electricity to the walled city, residents managed to improvise, supplying the buildings with illegal power “tapped somewhere in the outer world” via a network of dangerous cables “that are disconnected and replaced with new cables again and again,” according to the 1989 documentary, Kowloon Walled City. The cables hung in thick, erratic hanks above standing water, and were continuously bathed in dripping runoff from above. Why the entire place didn’t go up in flames is a mystery.

5. Don’t eat the food

As South China Morning Post reported in 2013, the walled city housed at least 700 industrial and manufacturing businesses. These businesses were operating illegally, outside the reach of government and health inspectors. Many of them produced food such as noodles and spring roll wrappers, the workers toiling in unsanitary conditions for 12 hours a day, seven days a week. Rats were frequently found within food production sites in the walled city. And the food produced was typically not meant for the locals, but for high-end restaurants in outer Hong Kong. According to the Wall Street Journal, 80% of fish balls, Hong Kong’s “ultimate gourmet delicacy,” were manufactured within Kowloon Walled City.

6. Become a dentist

According to former resident and Triad member Tang Kam-cheung, Kowloon Walled City was known for three things: opium dens, brothels, and dentists.

That’s right: dentists.

There were, he recalls, “a lot of dentists. Unlicensed dentists.”

As the Kowloon Walled City documentary crew discovered, “they are neither medical doctors nor dentists. The dental treatment, the molding of dentures, they learned it from their fathers or uncles, [working] from an early age, since childhood. … They have [no formal schooling] or diploma.”

Could you make it in the walled city? I’m 100% sure I couldn’t.