The Summer Palace in Beijing is one of the most famous gardens in the world.
The Summer Palace (Yíhé Yuán) is (AFAIK) the biggest classical garden in China, occupying 294 hectares. It was built by the order of the Emperor Qianlong (in 1750 according to wikipedia, or in XI-th century, according to other sources) under the inspiration of the aesthetics of the gardens of Suzhou
[http://beta.lomography.com/magazine/locations/2009/01/14/master-of-the-net-garden":http://beta.lomography.com/magazine/locations/2009/01/14/master-of-the-net-garden]. It is also one of the most famous gardens in the world.
The main elements of the garden are Longevity Hill and hand-made Kunming Lake. The largest island in the lake is Nanhu Island, connected with the shore by the Seventeen-Arch Bridge.
The Summer Palace is located nearly one hour ride my subway and bus from the central Beijing and can be a great half-day escape toward harmony, aesthetics and nature.