Noun
A half circle; a semicircle.
A semicircular place, as a semicircular arena, or room, or part of a room.
Source: Webster's dictionaryBoth the Brussels and Strasbourg hemicycle roughly follow this layout with only minor differences. citation The hemicycle design is a compromise between the different Parliamentary systems. Source: Internet
Poland Chamber of the Sejm showing the hemicycle seating pattern. Source: Internet