Historical notes
The need of special buildings for the ludi gladiatori, the venationes and their machines, was felt rather late in the Roman world and in Rome even later than anywhere.
Dio Cassius called the amphitheater built by Iulius Caesar a sort of venatorius theatreand it’s called amphitheatre as it is an amount of seats without the stage (C. Dio,XXXVI,58). For Vitruvius it means theatrum with tribunes all around.
The evolution of the amphitheatre, from a temporary and wooden unstable construction, to be a steady stone structure, happened in Regio I Campania where the ludi gladiatori involved and were held first. According to a letter by Strabo, in the ancient times, these kind of ludi were held also by the tombs, or in the Forum, or even during the funeral banquets (which confirm the funeral origin of the games).
Usually the walls and the structures of the amphitheatre were raised on a flat ground: for the Coliseum, the most famous amphitheater, was chosen Nero’s garden pool. But we have other examples where the material was excavated from the center as from a quarry and used for the nearby structures. Sometime the quarry was excavated in a high ground so that supporting walls were not needed. Or, the amphitheatre leaned to a hill so to have a perimetrical wall reduced in its length.
The ellipse’s dimensions vary between the greatest, the Coliseum (Amphiteatrum Flavium) with axis of 187 mts x 155 mts, and the shortest, in Ventimiglia, measuring only 35 mt x 31 mt.
Another feature of an amphitheather is the ratio between the max axis and the min one of the arena; it is a measure to realize how much the ellipse is “smashed”. The more similar to a circle (1,05) was the one in Lucus Feroniae (by Capena, Italy), the most longish (2,09) the one in St.Bernarde de Comminges.
Features and structural elements
ellipse’s axes
number of orders: the number of different levels for the arches.
arena: a long sand track
porta triumphalis: a gate for the entrance of the pompa gladiatoria, the initial parade of the games.
porta libitinaria, for transporting the dead or wounded gladiators.
porta sanavivaria, reserved to the exit for the gladiators who have had their life spared
cavea: the place where the audience was; it was divided by aisles where the admittance staircases for the public led; they were on the long sides and on the opposite side from the carceres. The stairs of the cavea were on different levels, divided horizontally by praecinctiones, and vertically by scalaria (stairs). The ideal inclination for the caves was 37 degrees, like in the Coliseum.
pulvinar: a stage on a high position, hosting the deities statues to whom ludis were offered.
(From “Il Colosseo, Architettura, Storia, spettacoli e curiosità dell’Anfiteatro Flavio, il piu’ celebre tra i monumenti dell’antichità romana”. Roberto Luciani. De Agostini, 1990)
Specialized sites on amphitheaters:
1. Bill Thayer’s site about amphitheaters