- A theater or concert hall with a central arena surrounded bycircular or semicircular seating. Examples include the Royal AlbertHall, London, and Madison Square Garden, New York. Sometimes the termis used for the first tier in the gallery of a theater. The word isfrom the Greek meaning 'double theater'; it arose because the firstGreek theaters were semicircular or semioval, rather than having seatsall around the acting area. The amphitheatres of the Romans, builtin cities throughout the Empire, were often used for dramatic performancesas well as for such spectacles as gladiatorial contests. Famous amphitheatresinclude the Colosseum in Rome, opened in 80 AD, whose four-storeystructure could accommodate about 50,000 spectators on its marbleseats.