Two main influences have shaped the concert auditorium: precedents and science. Design according to precedent was of necessity the norm prior to 1900, the date from which a science of room acoustics can be said to have originated. During the twentieth century, reliance more on precedents or more on science has been a theme for discussion with variations. Conservatives have relied on tried and tested precedents. More ambitious designers have responded to new scientific ideas, though in some cases these ideas have proved to be misguided. In terms of auditorium plans, nearly all concert halls can be related to one of four traditional forms, as illustrated in Figure 1.1: the fan-shape, the arena, the Baroque theatre and the rectangular plan (Barron, 1992). Examples of concert halls conforming to each plan are to be found in this chapter and the next one. Only two of these plans have emerged as suitable for concert performance.