From the outside, it was 2.7 hectares of fortress. On the inside, it was home to 33,000 people living among rubbish-ridden alleyways and side by side with drugs, prostitution, gambling and rats. Some called it hell on earth, others called it the biggest slum in the world. And in March 1992, it all came down. The history of the Kowloon Walled City dates from the Sung Dynasty of 960-1297, when it began as a small fort to house the imperial soldiers who controlled the salt trade. In the second half of the 19th century, the Chinese, facing invasion by the British, who held Hong Kong island, expanded it into a proper garrison town containing soldiers, and officials and their families. The walled city became the only part of Hong Kong China was unwilling to cede to Britain under the 99-year lease of Kowloon and the New Territories in 1898. The British agreed that China could keep the city - until the colonial administration for the area was established. But the Chinese never dropped their claim of jurisdiction, and the sovereignty fight remained unresolved - the result being a lawless enclave and a hotbed of criminal activity. In December 1899, after several unsuccessful attempts to clear the city, the British announced their jurisdiction was to be extended to include it, and the Chinese officials left. The city became isolated, and while parts were leased to church-run, charitable institutions, much was left to fall into disrepair. By 1940 only the Lung Chun School, its gateway and one private home remained. When the Japanese invaded in World War II, they demolished the oldest standing part of the Walled City: its wall, which was used in work on Kai Tak airport. But the destruction didn't prevent Chinese refugees flocking to the site after the war. Rents were low, and there were no concerns about taxes, visas or licences. By 1947 there were 2,000 squatter camps on the site; permanent buildings followed, and by 1971 10,004 people occupied 2,185 dwellings in what was still referred to as the Walled City. By the late 1980s, it was home to 35,000 people. The government tried to clear the city several times, but on each occasion the residents threatened to create a diplomatic incident. Their attitude - handy when it came to keeping the authorities' nose out of their business - was that the city was part of China and would never belong to Hong Kong. And to avoid damaging Sino-British relations, the government adopted a largely hands-off policy towards it. The city again became a hotbed for criminal activity: opium dens, heroin stands, brothels and dog restaurants all multiplied in the '50s and '60s, with police usually turning a blind eye. There were three reasons for that: they were politically hobbled, some were bribed, and it was too dangerous. Real power lay with the triads. But the position changed in the '70s, when a wave of anti-corruption campaigns removed most criminal elements in the authorities. No longer protected, the triads became weaker. The height of the walled city rose with the rest of Hong Kong. In the '50s, housing usually consisted of wooden and stone low-rises; in the '60s, concrete buildings of four or five storeys appeared, and in the '70s many were replaced by blocks of 10-storeys or more. The site became chaotically cramped, with buildings so close to each other that in some it was impossible to open a window. Low rents also meant many small factories, with toys, plastic goods and food among the biggest products. The factories may have brought their owners decent incomes - but they also brought the city more rubbish, fire hazards and pollution. Limited interference by the authorities also meant limited welfare: apart from basic municipal services such as rubbish collection, residents had to rely on each other to maintain living conditions. That bred a close-knit community of people willing to support each other. The Walled City's fate was finally decided with the Joint Declaration of 1984: it was to be flattened and replaced by a park. Three cannons and a few stone inscriptions remain of the garrison, and the school gateway has been restored to its Qing dynasty condition. The school now houses a small photographic exhibition commemorating the city. Ask former residents what they miss most about the Walled City and most say the friendship. The neighbourhood association, the Kowloon Walled City Kai Fong Welfare Promotion Committee, set up in 1963, still exists. It has several hundred members, most of whom have settled in the Wong Tai Sin and Tseung Kwan O areas, and is about to build permanent headquarters in Wong Tai Sin. Old city gate: The location of the old city gate was marked by a building called East Gate House. Lung Chung Road: Lung Chun Road was the first street built inside the fort. In a fortified Chinese city, Lung Chun is the name usually given to the main road leading from the city gate. 'Lung' means dragon, and 'chun' usually means the bridge over the moat around a fort. Factories: Thanks to its plastics and toy factories, the Walled City became the most polluted area of Hong Kong. Cannons: Two of the remaining cannons - cast in 1802 and unearthed in 1970. Well: The well, the only source of water for the garrison, was sunk before the wall was constructed. It was closed in the late '50s and replaced by street taps. Lung Chun School: Lung Chun school was built in the 1850s for the children of mandarins and imperial soldiers. It became a free secondary school in 1905 but was destroyed by fire in A high-rise apartment block was built in the site. Yamen: The yamen, built in the early 1800s, served as a military headquarters. Lung Chun To: Lung Chun To, constructed in 1951, was where most mahjong parlours, opium dens and dog restaurants sprang up. There was also a number of striptease clubs - making the Walled City the only place in Hong Kong that they operated. Drug dealers used them to lure customers: they could advertise the shows, but could not advertise drugs, gambling or prostitution. Kwong Ming Gai: Kwong Ming Gai (Bright Street) was also the area's darkest street in the '50s and '60s: it was illuminated by candles placed on top of wooden stands and used by heroin addicts to 'chase the dragon'. In the '70s, when injecting heroin became more popular, addicts abandoned the wooden stands in favour of tin 'drug' huts in the south of the Walled City. They would queue to receive their injections and pay on the spot. But despite the gatherings of addicts, police found arrests difficult to make. According to ex-assistant divisional commander Dick Williamson: 'There were lots of escape hatches. Once people sensed there was a raid, you'd have people crawling out and running all over the place.' Tin huts: The tin huts, which sprawled across the southern side of the city and which included the 'drug huts', were cleared in the '80s. The Heung family: Hoping the eviction scheme which eventually cleared the city would entitle them to public housing, the Heung family of six moved from a roof-top hut in Hung Hom to the Walled City in the '60s. At first they lived in a 70-square-foot room in a two-storey house near Tung Tau Chuen Road, which they shared with seven other families. Several years later they moved to a two-bedroom flat on the fourth floor of a high-rise on Tai Cheng Street. 'Life was poor, but we were very happy,' said Heung Yin-king, the eldest daughter of the family. 'We had the best times in the first house, even though the rooms were so tiny there wasn't space for a dinner table - we ate from a board laid over the knitting machine and sat on the bed. Everyone got along, and it was great to have so many kids to play with. The second house was all right but had no taps, so as the eldest daughter I had the responsibility of hauling buckets of water from the public taps up four floors to the flat every day. That's why I'm so short!'