Temple of Heaven (Tian tan)

A Ming temple, Temple of Heaven or Tian tan was built by the Yongle Emperor, who also built the Forbidden City, as a stage for the important rituals performed by the emperor, or Son of Heaven. Chief among these were the supplication to the heavens for a good harvest and the Winter Solstice ceremony, which was supposed to ensure a favorable year for the entire kingdom. 
In those days it was believed that heaven was round and earth was square, so the architecture of the buildings (round, set on square bases) and the layout of the park (squared off at the Temple of the Earth end, rounded at the Temple of Heaven end) reflect this belief. 
The buildings are rich in symbolic detail - variations on the number nine, which represented the emperor; coloured glazes which represent heaven and earth; and pillars which represent the months of the year, the seasons and time. There are also echo stones where you can stand to hear your voice reverberate, and a circular echo wall which carries your whisper to the far side of the circle. 

The park is a popular place for morning tai-chi.

Practical Info

You can reach the Temple of Heaven on buses 39, 106, 110, or by underground rail - get off at Chongwnemen, Qianmen or Tiantandongmen.