Its diameter is 78 cm and thickness is 4 cm, made in Western Han Dynasty (B.C.206-A.D.23). According to historical record, it's one of the national treasures survived rarely in China.

The one side of the bronze mirror is so smooth that one can look himself at it like a modern glass mirror. On the other side of it, there're some graphs and Chinese characters, which says:

"The day when it's in the sunlight, the world will be at peace."

When an incident illumination e.g. the sunlight reaches at its smooth side a reflection vision will be formed on the plane place opposite the bronze mirror as it does to a normal glass mirror. However, what seems interesting and magical is that the reflection vision is exactly the same as graphs and characters shown on its back side, which seems that the mirror made of bronze has been penetrating -----a mystery remain through the ages.