The long history of Bozhou has left behind many places of historic interest, such as the Opera Theater, Huazu Temple, the Graveyard of Cao Cao's family, and the underground troop course. The Opera Theater, a major unit under state protection, was built during 1662 and 1722, the reign of Emperor Kangxi of the Qing Dynasty, around which there are such structures as an opera theater, a bel I tower, a drum tower, and the Hall to Lord Guan. These buildings are of high value for the study of architecture, opera, and painted sculptures of the Qing Dynast' Bozhou is also one of the four major producers of Chinese medicine.