The most densely populated place in the world, Kowloon Walled City, Hong Kong
Only thirty years ago, Kowloon Walled City was the most densely populated area on earth. After becoming unmanageable in the early 1990s it was razed, and the area is now a Chinese garden.
“In terms of market transparency, Hong Kong’s property market is not complicated for foreign buyers or investors, but in terms of the home price and total transaction costs, its property is relatively expensive to most foreign buyers."
By Knight Frank's latest index, Hong Kong is the world's most expensive market, where US$1m buys just 20 sqm. The same budget will only get you 39 sqm in Singapore, 48 sqm in Shanghai and 86 sqm in Tokyo, as per the index.