Did you know that the Chinese had air-conditioning back in those days - the floor were laid with bronze tiles. Below that were passages that had hot water passed through in winter for heating and in summer, iced water was used to cool the flooring.
The big urn around the palace are not decorative but were used to hold water for fire fighting. The urns were heated in winter to prevent the water from freezing over.
The great wall is just a great feat of human will and ingenuity that humbles us greatly.
