But the great work of this emperor, and the greatest architectural wonder of the world, was the amphitheatre, which he built on the ground covered by Nero's lake, in the middle of the city, between the Velia and the Esquiline. For magnitude it can only be compared with the pyramids of Egypt, and its remains are the most striking monument we have of the material greatness of the Romans. Though not the first of the amphitheatres which were erected, its enormous size rendered the erection of subsequent ones unnecessary. It was here that emperors, senators, generals, knights, and people, met together to witness the most exciting and sanguinary amusements ever seen in the world. It was built in the middle of the city, with a perfect recklessness of expense, and could accommodate eighty-seven thousand spectators, round an arena large enough for the combats of several hundred animals at a time. It was a building of an elliptical form, founded on eighty arches, and rising to the height of one hundred and forty feet, with four successive orders of architecture, six hundred and twenty feet by five hundred and thirteen, inclosing six acres. It was built of travertine, faced with marble, and decorated with statues. The eighty arches of the lower story formed entrances for the spectators. The seats were of marble covered with cushions. The spectators were protected from the sun and rain by ample canopies, while the air was refreshed by scented fountains. The nets designed as a protection from the wild beasts were made of golden wire. The porticoes were gilded; the circle which divided the several ranks of spectators was studded with a precious mosaic of beautiful stones. The arena was strewed with the finest sand, and assumed, at different times, the most different forms. Subterranean pipes conveyed water into the arena. The furniture of the amphitheatre consisted of gold, silver, and amber. The passages of ingress and egress were so numerous that the spectators could go in and out without confusion. Only a third part of this wonderful structure remains, and whole palaces have been built of its spoils. [Footnote: Dyer, _Hist. of the City of Rome_, p. 245. Gibbon, chap. 12. Montaigne, _Essays_, in. 6. Lipsius, _de Amphitheatro_.] [Sidenote: Rebuilding of the Capitol.] [Sidenote: Arch of Titus.]