In an arena theater, also commonly referred to theater-in-the-round (especially in Britain), there is an audience on every side of the performers; in effect there are four fourth walls. This type of theater was most common in ancient Greek theater, but it has continued as a creative alternative to the more common Proscenium format. The most well-known arena theater in the United States is the aptly named Arena Stage Company in Washington, D.C.; however there are many other contemporary examples.