We now turn to the _Coliseum_, originally called The Flavian Amphitheatre. This vast building was begun in A.D. 72, upon the site of the reservoir of Nero, by the Emperor Vespasian, who built as far as the third row of arches, the last two rows being finished by Titus after his return from the conquest of Jerusalem. It is said that 12,000 captive Jews were employed in this work, as the Hebrews in building the Pyramids of Egypt, and that the external walls alone cost a sum equal to 17,000,000 francs. It consists of four stories, the first Doric, the second Ionic, the third and fourth Corinthian. Its circumference is 1641 feet, its length is 287, its width 182, its height 157. The entrance for the emperor was between two arches facing the Esquiline, where there is no cornice. Here there are remains of stucco decoration. On the opposite side was a similar entrance from the Palatine. Towards S. Gregorio has been discovered the subterranean passage in which the Emperor Commodus was near being assassinated. The numerous holes visible all over the exterior of the building were made in the middle ages, to extract the iron cramps, at that time of great value. The arena was surrounded by a wall sufficiently high to protect the spectators from the wild beasts, who were introduced by subterranean passages closed by huge gates, from the side towards the Cœlian. The _podium_ contained the places of honour reserved for the Emperor and his family, the Senate, and the Vestal virgins. The places for the other spectators who entered by openings called _vomitoria_, were arranged in three stages (_caveæ_), separated by a gallery (_præcinctio_). The first stage for knights and tribunes, had 24 steps, the second (for the common people) 16, the third (for the soldiery) 10. The women, by order of the emperor, sate apart from the men, and married and unmarried men were also divided. The whole building was probably capable of containing 100,000 persons. At the top, on the exterior, may be seen the remains of the consoles which sustained the _velarium_ which was drawn over the arena to shelter the spectators from the sun or rain. The arena could on occasions be filled with water for the sake of naval combats. Nothing is known with certainty as to the architect of the Coliseum, though a tradition of the Church (founded on an inscription in the crypt of S. Martino al Monte), ascribes it to Gaudentius, a Christian martyr, who afterwards suffered on the spot.[70]