Kowloon Walled City was once the most densely populated area in the world with 35.000 inhabitants crammed into a virtually solid 14-storey high mass of building in the centre of Kowloon, Hong Kong. In the years running up to the return of the British colony to China, the mainland finally agreed to the demolition of the city and the decanting of its population. Kai Tak City is located on the runway of the now disused Kai Tak Airport in the centre of Kowloon, Hong Kong. The urban design proposal consists of a number of catalyst delements to provide the infra-structure for the growth of a new city: The Wobbly Bridge for Kai Tak City links the new city with the mainland. It is made from bamboo ropes. The swaying caused by pedestrians crossing the bridge sets a number of generators into motion which translate the resonance forces into electric energy which is used to power the street lighting of the city. The model of the bridge was awarded a Royal Academy Architecture Award in 2003. The project was recently published in Bartlett Designs edited by Iain Borden.