Since this chapter was printed, the great excavations that have been carried on in Rome have brought to light many remains of the old Aqueducts in places where they were not previously known or thought of. These are so numerous that we can do little more than mention them, beginning at the Sessorium, where the principal aqueducts entered Rome. In the Sessorian or Palatian gardens, now those of Santa Croce in Gerusalemme, a pit was dug in the reservoir which was used for the Thermæ of S. Helena, which is a large cistern of two narrow chambers, with others similar under them; this was ascertained by digging this pit. Remains of other reservoirs along the line of the north wall of the garden, which is made out of the old aqueduct, were brought to light more clearly. Just outside of this garden is the road from the church of Santa Croce to the Porta Maggiore[211], which is carried on a bank of earth that was the boundary of the Sessorian garden, and on the outer side of it, this bank is supported by a wall of the time of Constantine, no doubt built when his mother, S. Helena, resided there. Just beyond this bank, and in the great foss of the ancient fortress, are two large reservoirs close together, one on either side of the foss. These appear to correspond with the _Gemelli_, or twin reservoirs of Frontinus; an excavation made here was stopped by water, but enough was seen to make it evident that there were other chambers under them, and that they were very deep, but have probably been used for one of the later aqueducts, at a higher level also. It was very usual to carry one aqueduct nearly over another, in order that the older subterranean reservoir might receive the surplus water of the later and higher ones. It is probable that in this instance the Claudia and Anio Novus had each a reservoir here on the higher level, and that the water of the two was here united and carried on along the Cœlian Hill in one _specus_, on the arches of Nero, to the middle of the city.