Located northwest of Beijing's center, the Summer Palace is the most completely preserved Garden of Qing Dynasty in the largest scale, as well as a renowned classical imperial garden in China. Built in 1750, it covers an expanse of 2.9 square kilometers, three quarters of which is water. The Summer Palace is mainly dominated by Longevity Hill and the Kunming Lake; there are more than thirty sets of classical-style architectural structures. The Summer Palace was exploited into a garden in 1928; it was declared an important heritage site under state protection in 1961 by the State Council; and in December 1998, UNESCO included the Summer Palace on its World Heritage List.