The style of brick building used in these Thermæ, recalls that of the Basilica of Constantine, where we see the bricks irregularly and hastily laid; and the whole of the architectural details which have been preserved seem to point to the same period. Positive evidence of the date and the builder is not however wanting. An inscription, which was still to be seen two hundred years ago in the thermæ, and which has been partially preserved to us, when compared with three others which were found in the neighbourhood, shows that Maximianus gave orders for building these thermæ when he was absent in Africa, during his Mauretanian campaigns, and intended them to be dedicated to the honour of his brother Diocletian. The dedication took place after the abdication of Diocletian and Maximianus, when their successors Constantius Chlorus and Galerius Maximianus had begun their reign, A.D. 305, but before the death of Constantius in 306. The old chronologers place the date of the commencement of the buildings in 302, which agrees very well with the date of the Mauretanian campaigns of Maximian. Baronius accounts for the preservation of so large a part of these thermæ by the statement that they were considered to be a monument of the Diocletian persecution. There was a tradition, he says, that Diocletian, after dismissing some thousands of his soldiers because they held the Christian faith, compelled them to work as slaves in the erection of his thermæ, and ordered them to be martyred when they had finished the building. It has also been said that the bricks are in some cases marked with a cross, but this is not well authenticated. [Illustration: THE SERVIAN WALLS.] At the end of the fifth century, the baths are mentioned by Sidonius Apollinaris as still used, but at the time of the visit of the anonymous writer of the Einsiedlen MS., probably about A.D. 850, they were evidently in ruins. Among the ruins have been found, from time to time, a number of busts of the Emperors Diocletian, Maximian, Galerius, and Constantine, and also the well-known busts of philosophers now in the Farnese collection at Naples. The great fountain now in front of the railway station is supplied by the water brought along the course of the ancient Aqua Marcia. [Sidenote: The Servian Agger.]