From these remains we pass to the Circus of Caracalla, not that it was built by that emperor, for it is probably of a much later period, but it was known from medals that Caracalla erected a circus, and the antiquaries could not tell where to find it, while here they had a circus without a name. Whoever built it, it is a very interesting ruin, because it exhibits more perfectly than any other, the arrangement of the ancient circus. The surrounding walls are constructed like those of the court of the mutatorium, with alternate layers of brick and small stones; the continued vault which supported the seats, is of rubble, but with large earthen vases in the upper part, to lighten the work. The line of _Carceres_ which forms the square end, if I may use the word _square_ so loosely, is oblique in position with respect to the side walls, and curved in itself, in order to put all the chariots upon an equality at starting; and the _spina_ for a similar reason is neither along the middle of the arena, nor exactly parallel to one of its sides, but so disposed that the passage gets narrower through its whole progress. At the semicircular end is the _Porta Triumphalis_,[6] through which the victor left the circus. The obelisk which now embellishes the Piazza Navona, once decorated the spine of this place. Overlooking this circus, are various ruins, of which we may reckon five distinct fragments, each at some distance from the other; and a long terrace, supported in part upon vaults, to one of which you still find an entrance. The stucco is still remaining, and we observe painted lines drawn very neatly and correctly round panels, of which the ornaments in the middle have been taken away: from what remains, we may conclude that the whole was well finished. Some of these fragments of edifices have been supposed to belong to the temple of Honour and Virtue, built by Marcellus, after the conquest of Sicily, in the year of Rome 544; for this, however, there is not the shadow of proof, and the style of construction, of rubble faced with brick, is similar to that of imperial times.