Theater in the round
A theater in the round is a performance space in which the audience sits on at least three sides of the stage (for plays, the back of the venue is usually kept hidden for scenery changes, and actor entrances and exits; some musical concert venues allow seating on all sides, that is, completely in the round).
Theaters in the round were common in ancient times, and although it never fell completely into disuse, the modern theater as it developed in Europe and America, generally favoured the proscenium theatre, which allows for grander productions. When the theater in the round format was revived in the mid-twentieth century, it was considered avant garde and progressive.
One advantage of theatres in the round is that they can dramatically reduce the need for lavish or complicated sets, in terms of curtains and scenery. A disadvantage is the extra staging considerations, rather that the actors being able to focus to one direction, the director and set designer have to consider what the production will look like from different points of view, and how to eliminate or at least reduce the problem of characters having their backs to the audience.