KOWLOON Walled City's transformation from slum to 'oasis' should inspire the restoration of more historical sites, Governor Chris Patten said yesterday. Mr Patten, speaking at the opening ceremony of the award-winning public park, hopes more sites can be salvaged. And the first step will be taken early next year with the first territory-wide survey of historical buildings and structures. The survey, made possible by $4.14 million sponsorship from the Hong Kong Jockey Club, will help formulate a strategy on heritage preservation. Next year the Antiquities and Monuments Office is to conduct an archeological survey, updating findings made during the only previous study in 1983. Mr Patten applauded the 'fantastic transformation' of Kowloon Walled City. The $61 million park, in the style of the early Qing dynasty, is in stark contrast to the squalor and lawlessness which infested the area until bulldozers flattened the 2.7 hectare site in 1993. The Walled City - the only part of Hong Kong which the imperial Chinese government refused to hand over to the British - became famous for its prostitutes, opium dens and unlicensed dentists. In 1987 the British and Chinese governments reached agreement to tear down the slums, once home to 33,000 people. Mr Patten said the agreement had enabled the Government to change the area 'from a black spot to a beauty spot that all can treasure', and 'an oasis of leisure', amid the surrounding urban sprawl. The park features pavilions, winding galleries, rockeries, stone paving and wood and bamboo carvings. Most of the construction materials were imported from China. Two stone tablets bearing the Chinese characters for 'south gate' and 'Kowloon Walled City' were discovered during excavation and can be traced back to 1886, during the Tao Kwong era of the Qing dynasty.