The arts have traditionally employed devices that seem designed to assist the spectator in lifting the occasion out of any practical context and placing it in a special, autonomous space of its own. The pedestal and the stage raise sculpture and theatre above the plane of ordinary life, the frame and the proscenium arch separate art and performances from their surroundings, special halls for the visual arts and for music provide what the cathedral does for religious worship, a sanctified space removed from the concerns of daily life.

Proscenium arch

Meaning

Noun