=Amphitheatre.=--The most magnificent of the amphitheatres was the Flavian, known since the eighth century as the =Colosseum=, probably from the colossal statue of Nero which once adorned it. Its plan is elliptical, the main axis being about 615 feet and the shorter about 510 feet; while the arena, which is oval, is 281 feet long by 177 feet wide. The number of spectators that it could accommodate has usually been stated as 87,000; but the calculation is now said to have been based on a misapprehension of the records and has been corrected to 45,000 seats and standing room for 5000. The exterior comprises four stories. The three lower are composed of arches supported by intermediate piers which are ornamented with columns, respectively, of the Tuscan, Ionic, and Corinthian orders. The fourth story, which, when the amphitheatre was completed in <small>A.D.</small> 82, appears to have been of wood, presents a wall adorned with Corinthian pilasters. Between these, projecting from the cornice, were corbels, pierced to hold the poles that sustained the _velarium_ or awning. The imposing character of the exterior is due not only to the structure’s immense size, but to the difference in unity secured by the application of the three orders, and to the magnificently sweeping lines of the entablatures. The interior shows the arena surrounded by a smooth wall, above which the seats rise in concentric tiers to the height of two stories. Here they are bounded by a wall, through which are entrances to the seats while it also acted as a parapet to the upper gallery. The fourth story formed a continuous peristyle. The whole area for spectators was called the _cavea_. The place of honour was the circle nearest to the arena, called the podium, in which sat the Emperor, senators, principal magistrates, Vestal Virgins, and the provider or “Editor” of the show. In the amphitheatre at Nîmes seats in the podium were also assigned to the various guilds, whose names are still inscribed upon the seats with the number of places reserved for each. The principle of construction adopted in the Colosseum, as may be seen from the plan, is that of wedge-shaped piers, radiating from the arena to the exterior. These were connected by vaults which ran downward toward the centre and also in concentric rings, forming passageways to all parts of the cavea. The system is one of concrete vaulting resting on piers of the same material, the latter being reinforced by tufa where the pressure was greater and in the parts of greatest strain by blocks of travertine, four feet thick, sheathed with brick work. “The supports have been calculated at one-sixth of the whole area of the building.”