Behind this wall, under the path in front of the _podium_, are the dens for the wild beasts. At the back of each den, in the corner, is a vertical aperture about four feet square, descending from the passage in front of the _podium_; this descends to ten feet from the ground only, and was for the men to go down and feed the animals below without being exposed to danger. In front of each den is a hole in the original brick pavement, sometimes with a bronze socket remaining in its place. These sockets (of which there are a great number in the pavement) are evidently made for a pivot to work in each, and these pivots must have been the lower end of a post for a capstan to wind the twenty-one feet of cord upon, when the animal in his cage was pulled up to the top, and the trap-door opened by the same cord from below, to let him jump out when required for effect on the stage[4]. It is recorded by contemporary authors that on several occasions a hundred lions leapt on to the stage or arena at once. Some very curious _graffiti_, or scratchings on marble, by the workmen of the third century, have been found, one of which represents a hunt of wild beasts on the arena, in which apparently the dogs have broken loose[5]. Another shews the framework of the netting of gilt wire in front of the lower gallery[6]. There are five different representations of the Colosseum on the coins or medals of the Emperors, one of Vespasian, two of Alexander Severus, and one of Gordianus. These all appear to have been made from the architect’s designs before the work was completed; there are slight variations in the accessories, and the upper storey varies considerably. That of Gordianus has for the legend or inscription— MVNIFICENTIA GORDIANI AVG.[7] This great tufa wall, on the inner line, has evidently been much shaken by earthquakes in different parts, and the heads of the apertures (which are square-headed when original) have frequently had arches introduced, and are supported by brick walls of different periods[8]. In one instance an arch of tufa had been much shaken, and this is supported by a brick arch of the time of Nero[9]; there are also many other walls and arches of his time in different parts of the building, which make it clear that this building was the amphitheatre for the _gymnasium_ and the _naumachia_ of Nero. It is the natural site for it, close to his great palace, and the remains of that of Scaurus made him excellent foundations to build upon, according to the fashion of his own time, which was of brick, of the finest brickwork in the world. Those whose eyes are accustomed to it can never mistake the brickwork of the time of Nero; his awning is also mentioned; and the first book of the Epigrams of Martial is full of incidents and spectacles in this amphitheatre.