In the first volume of Le Antichità Romane, Piranesi traces the progress of the Neronian pipeline by representing its route in the Topographical Map of the Roman Aqueducts and depicting its most important sites in various etchings. The aqueduct brought the waters of Acqua Claudia and Anione Nuovo from Porta Maggiore to the Aventine Hill, branched off to the Caelian Hill to reach its slopes and, by the means of a castello, supplied the structures there and, in particular, the so-called Nymphaeum of Nero. From the Caelian Hill, a last and later additional pipeline ran to the Palatine Hill. 

What Piranesi represented in this etching was the best-preserved substructure of the Caelian complex, which corresponded to the eastern side of the platform on which the upper architecture rested. Variety, a quality always pursued by Piranesi, is enhanced in his reconstruction of the wall structure, as it was formed by the alternation of deep quadrangular or semicircular niches opening in the masonry face, which was also characterized by smaller niches. Thanks to the luminist effects of his use of chiaroscuro, Piranesi generates a lively interweaving of empty and full spaces.  

Beyond his representation in this image, the eastern masonry that is its subject is reproduced in plan in the Map of Rome (no. 203) and described in that map’s index, as well as in the Topographical Map of the Roman Aqueducts. It is then represented in detail in the Plan of the Nymphaeum of Nero, in which it is indicated in the main plate (12) and detailed in the figure F. IV, which represented with a trompe l’œil effect as a marble fragment like those of the Forma Urbis.  

Piranesi tried to interpret the remains of the complex and to give his own explanation of the site. When Nero took power in 54 CE, the huge platform hosted a monumental temple in honor of Claudius, which was still under construction. The new emperor decided to include it in the great project of his Domus Aurea, transforming the structure into a huge nymphaeum. He was aware that the structure had to be higher, as what emerged from the ground in the eighteenth century (and as a result of excavations) was of course the upper level, with the culminating water conduit. According to his studies, the substructure that supported the Caelian Hill functioned also as theatrical wings to the Stadium that emperor Domitian built in the valley beneath, as indicated both in the etching’s key (B) and in the Index (no. 202 and 203). Piranesi imagined an articulated plan for the Caelian complex, described in the long caption of the Plan of the Nymphaeum of Nero. Squares, reception and banqueting halls, fountains, water displays, and temples were located around the large central stagno or pool, indicated at “6” in that plan.  

Here and in the etching depicting the Ruins of the Neronian Arches on the Caelian Hill that appears on the same page, Piranesi used dramatic one-point perspective to create a long view which rendered the magnificence of huge ancient structures. The staffage figures seem infinitely small in comparison, and they looks at the structure with what seems to be a mixture of wonder and dismay. The silence we can almost hear surrounds everything, and even the herd of microscopic goats seems to be under the dumb and melancholic spell of the lost grandeur that Piranesi meticulously represents in images and texts. (CS)