There are some things to visit in Wan Chai, like the Hong Kong Convention & Exhibition Center, the Museum, the Xinyi Hall, where the ceremony marking Hong Kong's return to China was held in 1997. and Bauhinia Square. You can also visit Causeway Bay, which is a major Wan Chai shopping center.
And about Kowloon, it actually was a walled city.
"The history of the Walled City (known as Kowloon then) can be traced back to the Song Dynasty, where it served as a watchpost defending the area against pirates and managing the production of salt. It was rebuilt as a fort in the mid-1800s on the same site on the Kowloon Peninsula of Hong Kong. After the ceding of Hong Kong Island to Britain in 1842 in accordance to the Treaty of Nanjing, the Qing (Chinese) authorities felt it necessary for them to establish a military/administrative post to rule the area and to check further British influence in the area.
Kowloon Walled City, 1915The Convention for the Extension of Hong Kong Territory of 1898 which handed additional parts of Hong Kong (the New Territories) to Britain for 99 years excluded the Walled City, with a population of roughly 700, and stated that China could continue to keep troops there, so long as they did not interfere with Britain's temporary rule. Britain quickly went back on this unofficial part of the agreement, attacking Kowloon Walled City in 1899, only to find it deserted. They did nothing with it nor to the outpost, and thus sent the question of Kowloon Walled City's ownership squarely into the air. The outpost consisted of a yamen, as well as other buildings (which eventually grew into a low-lying, densely packed neighborhood within the walls), in the era between the 1890s and the 1940s. The enclave remained part of Chinese territory despite the turbulent events of the early 20th century that saw the fall of the Qing government, establishment of a Republic of China in 1911 and later, the People's Republic of China in 1949.
The Walled City remained a curiosity - and a tourist attraction where British colonials and tourists could have a taste of the old China - until 1940, when during its WWII occupation of Hong Kong, Japan evicted people from the city, and then demolished much of the city - including the wall - to provide building materials for the nearby Kai Tak Aerodrome."
"By the early 1980s, Kowloon Walled City had an estimated population of 35,000. Being a lawless land, the city was notorious for its excess of brothels, casinos, opium dens, cocaine parlours, food courts serving dog meat, and secret factories. The Kowloon Walled City was also infamous for its ridiculously high number of unsanitary dentist clinics, since this was where unlicensed dentists could operate without prosecution.
[edit] Evacuation and demolition
Kowloon Walled City before its demolition.Over time, both the British and the Chinese governments found the massive, anarchic city to be increasingly intolerable - despite the low reported crime rate. The quality of life in the city, sanitary conditions in particular, was far behind the rest of Hong Kong.
After the Joint Declaration in 1984, the PRC agreed with British authorities to demolish the City and resettle its inhabitants. The mutual decision to tear down the walled city was made in 1987.
At that time, it had 50,000 inhabitants on 0.026 km², and therefore a very high population density of 1,900,000 / km². It was allegedly the most densely populated spot on Earth.
Evacuations started in 1991 and were completed in 1992. The government spent up to HK$ 3 billion to resettle the residents and shops. Some residents were not satisfied with the compensation, and some even obstructed the demolition in every possible way.
The 1993 movie Crime Story starring Jackie Chan was partly made in the deserted Walled City, and includes real scenes of building explosions. Kowloon Walled City was destroyed in the same year. Also, as the Walled City was beginning to be torn down, a group of Japanese explorers took about a week to tour the empty walled city, making a sort of map and a cross section of the city.[2]
After the demolition, a park was built in its place with construction started in May 1994."
http://en.wikipedia.org/wiki/Kowloon_Walled_City