Kunming Lake
Around 1749, the Qianlong Emperor decided to build a palace in the vicinity of Jar Hill and the Western Lake to celebrate the 60th birthday of his mother, Empress Dowager Chongqing. In the name of improving the capital's waterworks system, he ordered the Western Lake to be expanded further west to create two more lakes, Gaoshui Lake () and Yangshui Lake (). The three lakes served not only as a reservoir for the imperial gardens, but also a source of water for the surrounding agricultural areas. The Qianlong Emperor collectively named the three lakes "Kunming Lake" after the Kunming Pool () constructed by Emperor Wu (r. 141–187 BCE) in the Han dynasty for the training of his navy. The earth excavated from the expansion of Kunming Lake was used to enlarge Jar Hill, which was renamed "Longevity Hill". The Summer Palace, whose construction was completed in 1764 at a cost of over 4.8 million silver taels, was first named "Qingyiyuan" ().