How have high-density, high-rise planned communities become the predominant housing choice of Hong Kong residents and a vital feature of the city’s vertical urbanism? This article reconstructs the history of a gigantic housing estate called Mei Foo Sun Chuen, which was completed in Hong Kong between 1968 and 1978 by an American joint venture led by Mobil Oil Corporation. The estate was redeveloped from a former oil depot into a vast housing estate of 99 residential towers for 80,000 tenants. By the time of its completion, the estate was the largest privately financed residential development in the world, and it was heralded as the first high-rise planned community in Hong Kong. In studying Mei Foo Sun Chuen, this article discusses how a mega-scale residential development established a new dimension of Hong Kong’s new middle-class housing market. It argues that Mei Foo Sun Chuen’s new idea of a planned community, its modern flat design, and its comprehensive housing management met the requirements of a nascent middle class, which demanded a comfortable lifestyle that Hong Kong’s traditional housing market could not provide at the time. Since the completion of Mei Foo Sun Chuen, its popular housing model has proliferated throughout Hong Kong.