Suetonius tells us "he made a reservoir like unto a sea," which no doubt was afterwards used to supply the Colosseum with water for the naval combats. The quadrata of the Cœlian is artificially formed, and was evidently the great nymphæum connected with the Golden House. The water was brought from the Claudian Aqueduct at the Porta Maggiore upon arches, known as Nero's Arches, which ended near the Temple of Claudius, and these arches end in the gardens now supported by the walls forming the quadrata. The niches and hemicyclia on the east side, with their channels of supply behind, were evidently fountains, and the west side was probably similar in character, some of the specuses still existing. The front towards the Colosseum formed a grand cascade, the water falling into the reservoirs, the ruins of which we see in advance of the north wall of the quadrata, and at a lower level; from these it poured into the great stagnum or lake below, now occupied by the Colosseum. Signor Alberto Cassio found specuses all around the top, and a euripus or channel at the base; and stalactites and _opus signinum_ can still be seen there. _Turning to the right_ we pass under some medieval arches--flying buttresses--to support the church. _On the left_ are some remains of the house of Gregory; and, _on the right_, the wood of the Cœlian. _This hill was the ancient Clivus Scauri. To the left_ the steps lead up to THE CHURCH OF S. GREGORIO, whence Cardinal Manning takes his title. It is built on the site of the house of Gregory the Great, and was erected in the seventh century. Its interior is embellished with sixteen granite columns. The painting above the altar is by Sacchi, and the _predella_ beneath by Luca Signorelli. In a small side-chapel on the right is an ancient marble chair, and in a glass case numerous relics of various saints _Crossing the atrium_, in which is a monument to Sir Edward Carne, envoy from Henry VIII., _we come to_ the three detached chapels of-- S. SILVIA, which contains a beautiful fresco of the Father, with angels playing on instruments, by Guido Reni. It is built on the site of the house of S. Gregory, remains of which can be seen behind the chapel. S. ANDREW, containing the rival frescoes of Guido Reni and Domenichino--S. Andrew adoring the cross on his way to execution, and the Flagellation of S. Andrew. S. BARBARA, containing the marble table on which S. Gregory feasted every morning twelve poor pilgrims. On one occasion an angel is said to have honoured them with his presence. The statue of the saint was begun by Michael Angelo, and finished by his pupil, Niccolo Cordieri. Between the church and the chapels is a massive piece of tufa wall, supposed to have been part of the fortifications of the Cœlian Hill when it was a separate fortress. MUSEO URBINO.