On the road from the Forum Romanum to the Coliseum, after passing through the Arch of Titus, we descend between the platform and ruins of the Temple of Venus and Rome, and the remains called the lavacrum of Heliogabalus, mentioned previously, and, close to the south-western corner of the mass of substruction on the left, we find a conical column of brickwork about thirty feet high. A large breach on the side towards the Coliseum shows that the centre was pierced with a perpendicular pipe, and the eastern exhibits traces of having been divided into three ledges or stages. This conical building stood in the centre of a circular basin, the ruin of which has been traced out and restored. The shape would of itself point to the purpose which this building served, even if this were not rendered clear by the remains of a watercourse which descended to it from the Esquiline. The name Meta Sudans by which the ruin is known comes from the mediæval list of buildings known as the Curiosum Urbis, but the earliest authentic authority to which we can appeal for its date is a coin of Alexander Severus, A.D. 222. The passage of Seneca in which he gives the name Meta Sudans as being a spot at which the flute-players and trumpeters made a din by their practice, does not give us any information as to its position, and therefore we are not justified in assuming that the fountain was erected in Nero’s time.[67] The coins of Titus which represent the Coliseum do not show it. Cassiodorus and other chronologists place the date of the Meta Sudans in Domitian’s reign, and this agrees with the coins of Titus and also with the nature of the brickwork, which is of the Flavian era. [Sidenote: Arch of Constantine.] Near the Meta Sudans at the entrance of the Via di S. Gregorio stands the Arch of Constantine, which is the most completely preserved of all ancient Roman buildings. The name of Constantine, revered by subsequent ages, seems to have defended the archway from the barbarous spoliation which attacked most of the great monuments of Rome. The most interesting feature of this arch in the history of art is the proof which it gives of the decline of art in the fourth century. Some of the reliefs with which it is ornamented were taken from an older arch, probably that which formed the entrance to Trajan’s Forum, and those which are of Constantine’s time show a coarse and harsh style of execution in lamentable contrast to the flowing and delicate lines of the more ancient work by their side.