Inside of the Echo Wall is the Imperial Vault of Heaven. It has had several names since its construction in 1530: Taishen, Great Divine Hall and Hall for Appeasing Gods. The round, wooden structure has a blue tile roof accented with a golden sphere at the 64 foot peek. The 51 foot wide hall sits atop a beautifully etched marble platform. Celestial Treasure House was a sacristy for God’s tablets used by the emperor during ceremonies. The Imperial Vault of Heaven was rebuilt during the mid-18th century.