The hall of Supreme HarmonyⅤ

On the terrace of The hall of Supreme Harmony 

 This is an insense burner used to burn sandlewood during grand ceremonies. They are altogether 18 burners, representing the 18 provinces in Qing Dynasty.

Four bronze vats  are placed on the two sides outside the hall, which represent territorial integrity and were once used to store water to prevent fire.

Placed on the east and west sides of terrace are a bronze crane and a tortoise, the emblems of longevity.

The thing made of bronze is called JiaLiang. It was the standard of measurement indicating that the emperor treats everything fairly and knew everybody's conduct clearly.