The Temple of Heaven used to be the place where emperors of the Ming and Qing dynasties "made sacrifices to heaven" and "prayer for grains". It is round in the north and square in the south, meaning "round sky and square earth". The Temple of Heaven, first built in the 18th year of Yongle Period in the Ming Dynasty (A.D. 1420), has been expanded and rebuilt. As the largest heaven worship complex in the world, it is now a world cultural heritage and a key historical and cultural site under national-level protection.