The Summer Palace - also known as Yiheyuan - was built in 1750. In those days, it was called the Garden of Clear Ripples, and was a lakeside oasis where the royal court could escape the dust and heat of the Forbidden City in summer.
It was razed twice by foreign armies and completely rebuilt, most extensively by Empress Dowager Cixi in the 19th century. To fund her projects, she's said to have diverted a bunch of money destined for the Chinese navy. Ironically, one of her grand schemes was a marble boat that sits at the edge of the lake.
The grounds were declared a public park in 1924. These days, the 290 hectares (716 acres) of the 'Gardens of Nurtured Harmony' are madly popular with both tourists and locals.
The gardens are liberally scattered with temples, covered walkways, pavilions and bridges. Longevity Hill, one of the garden's main features, was constructed from the earth excavated when the lake was extended.