that it suggested
also a certain form. Our knowledge of the ancient basilica as a civil
structure is derived primarily from Vitruvius, and we learn about it also
from existing remains and from incidental notices in classical writers and
in inscriptions. If we review all the evidence we are led to the conclusion
that there did exist a normal form of the building, though many examples
deviated therefrom. This normal form we shall understand if we consider the
essential character of the building in the light of what Vitruvius tells us
of it.

Vitruvius treats the basilica in close connexion with the forum, to which
in his view it is an adjunct. In the earlier classical times, both in
Greece and Italy, business of every kind, political, commercial and legal,
was transacted in the open forum, and there also were presented shows and
pageants. When business increased and the numbers of the population were
multiplied, it was found convenient to provide additional accommodation for
these purposes. Theatres and amphitheatres took the performances and games.
Markets provided for those that bought and sold, while for business of more
important kinds accommodation could be secured by laying out new _agorae_
or _fora_ in the immediate vicinity of the old. At Rome this was done by
means of the so-called imperial fora, the latest and most splendid of which
was that of Trajan. These fora corresponded to the later Greek or
Hellenistic agora, which, as Vitruvius tells us, was of regular form and
surrounded by colonnades in two stories, and they had the practical use of
relieving the pressure on the [v.03 p.0471] original forum (Cic., _ad
Att._, iv. 16). The basilica was a structure intended for the same
purposes. It was to all intents and purposes a covered forum, and in its
normal form was constituted by an arrangement of colonnades in two stories
round a rectangular space, that was not, like the Greek agora, open, but
covered with a roof. Vitruvius writes of it as frequented by merchants, who
would find in it shelter and quiet for the transaction of their business.
Legal tribunals were also set up in it, though it is a mistake to suppose
the basilica a mere law court. The magistrates who presided over these
tribunals had sometimes platforms, curved or rectangular in plan, provided
as part of the permanent fittings of the edifice.

According to Vitruvius (v. 1. 4, cf. also vi. 3. 9) the building is to be
in plan a rectangle, not more th