A A. General Plan of this part of the _specus_ of the Aqua Appia, made into a stone-quarry for many years, and part of it still in use for that purpose, but another large part has been long out of use[236]. B. Entrances to the two parts, the steps distinguish that leading to the part excavated. C C. Section of part of the cave-quarry. D. View of that part of the _specus_ of the Aqua Appia which is built of squared stones, and has a terra-cotta water-pipe on each side of it. E E. Longitudinal Section of this part. F. Transverse Section of the same. DETAILS OF THE PLAN A. a a. Entrance to the cave or quarry. b b. Via di San Paolo, the carriage-road to that gate. c c. Via di Santa Sabba, the carriage-road up the hill to the south. d. Via di Santa Prisca, the road up the hill to the north. e e. The most perfect part of the _specus_ where it is built, and not merely a tunnel cut in the bed of tufa, as in other parts. f f f f. Windings of the tunnels for the Aqueducts. g g. Water-pipes of terra-cotta, by the side of the _specus_ in the part where it is built, and not merely cut out of the tufa. h. The _specus_ half filled up with the deposit of clay. i. Steps made to give access to the cave. THE AQUEDUCTS. PLATE XX. THE JUNCTION AT THE WEST END OF THE CŒLIAN, NEAR THE CLAUDIUM. PLAN AND SECTION. [Illustration: XX. AQUEDUCTS AT THE WEST END OF THE CELIAN] DESCRIPTION OF PLATE XX. THE JUNCTION AT THE WEST END OF THE CŒLIAN, NEAR THE CLAUDIUM. PLAN AND SECTION. A B C. Line of the Section. a. Colosseum. b. Claudium. c. Arch of Dolabella. d. Reservoir and Spring of water. e. Aqueduct of Nero. f. Cave-reservoir and Spring, with ten wells down into it, erroneously called a _vivarium_. g g g. Porticus of the Claudium. h. Church of SS. John and Paul. i. —— S. John of Mata. k. —— S. Maria in Domnica. l. —— S. Gregory. m. Clivus Scauri. n. House of the family of S. Gregory the Great. o. Villa Celi-Montana (formerly called Villa Mattei). p. Vineyard of Marchese Rappini. q. Ground called Orto Botanico. r. Place of S. Gregory. s. Arch of Constantine. t. Meta Sudans. u. Via Sacra. v. Summa Sacra Via. x. Proposed Drain, for turning off the water of this spring from the Colosseum. y. Branch of an existing subterranean drain under the Via di S. Gregorio, between the Cœlian and the Palatine. z. Excavation made in 1876 in the Vigna Rappini, in consequence of a land-slip; but nothing was found beyond an old quarry of tufa, at a great depth, and a branch of an aqueduct at nearly the same depth, the water having come originally from the spring in the cave (?) or quarry (?) called a _vivarium_. THE AQUEDUCTS. PLATE XXI. SECTIONS OF THE SPECUS OF EACH OF THE FIFTEEN AQUEDUCTS OF ROME. [Illustration: XXI. SECTIONS OF THE SPECUS OF EACH OF THE 15 AQUEDUCTS OF ROME] DESCRIPTION OF PLATE XXI. SECTIONS OF THE SPECUS OF EACH OF THE FIFTEEN AQUEDUCTS OF ROME.