Beijing Opera (Peking Opera) has been around since the late eighteenth century and was originally performed for the imperial family of the Qing Dynasty. It didn't fare well in the Cultural Revolution, when it was reviled as a corrupt luxury of the upper classes and outlawed. It was replaced by eight state-sanctioned operas that centered around class struggle.
Beijing Opera has enjoyed something of a revival, although its wailing and clanging aren't for everyone (kind of like Western opera, perhaps). Like so much of Chinese traditional culture, it's highly stylized, with dress, movement and even face paint taking on symbolic meaning.
If you go to a performance, you have a choice between a tourist-oriented, cut-down version, or the real deal. If you're going to go there at all, try a full performance: let it wash over you and enjoy the exquisite precision of the movement. Be warned, it's loud!
If you want to take in a quick dose of Beijing Opera, one pitched more at tourists, try the Liyuan Theatre, inside the Qianmen Jianguo Hotel (take Line 2 of the subway to the Hepingmen stop, then walk south for about 10 minutes).
If you want something more traditional, check out the Huguang Guild Hall, located just nearby on Hufang Lu.
