Iseum Metellinum: Porticus-Piscina

Imposing triportico with central water basin (piscina) found on a large terrace on the S slopes of the *Oppian, in the probable position of the *Iseum Metellinum and the sanctuary of Isis et Serapis of Regio III. This identification finds confirmation in the large number of Isiac statuary finds spread throughout this area. Two inscriptions found in the Via Labicana mention Isis (CIL VI 35571, 30915). Numerous sculptures of Isis and other Egyptian deities have come to light near the Church of SS. Pietro e Marcellino, in Via Merulana–Via Buonarroti and Via dello Statuto to the N, and at scattered points on the Esquiline (catalogued by Malaise and Roulet; cf. Lanciani 1897; Häuber 1990, 48 with n.108; de Vos 1997, 115-29, 132-36; ead. 1994, 145-47 with fig. 7; ead. 1993, 88, 91). Yet none of these finds was discovered in situ. The largest concentration of Isiac statuary was found in a wall 100 m W of SS. Pietro e Marcellino (Visconti). In 1897 Lanciani argued that the statuary had been scattered from an original location in the area S of Via Curva on high ground above Via Labicana, where most of the Isiac finds were concentrated (de Vos 1994, 132; Häuber 1990, 48, map 1). On this terraced area on the S slopes of the Oppian, significant architectural remains also came to light.Lanciani’s excavation drawings show a large, rectangular courtyard flanked by at least three porticoes of granite columns (Häuber 1990, 45-48 figs. 28-31, map 1). The orientation of the portico is only approximate, but its dimensions are known: 58 x 76 m (Häuber 1990, 45-46; de Vos 1997, 100, 147-49, figs. 207, 212; ead. 1994, 132). The use of granite columns suggests a date in the Imperial period; Lanciani dated the Porticus-Piscina between the Sullan period and the 1st c. A.D. (Häuber 1990, 100 with n.337). In the center of the courtyard was a piscina: 37 x 7 m (Häuber 1990, 46; de Vos 1994, 132). Water storage facilities were also found (Häuber 1990, 48). To the S of the E wing of the Porticus-Piscina stood a rotunda (diam. 13.6 m), its external walls constructed in tufa, its internal walls in brick (de Vos 1997, 135, 144, fig. 207 no. 6). Despite the absence of reliable data on its construction techniques, this rotunda is shown on our map; de Vos argues for an early date on the basis of the tufa used for its external walls; she also argues from architectural comparanda that the tholos form was associated with Isis (de Vos 1997, 134-35). To the S of the W wing of the Porticus-Piscina, at the corner of Via Bonghi and Via Poliziano, was a rectangular structure with an internal apse, its two surviving walls built in opus reticulatum of tufa (de Vos 1997, 136, 147 with fig. 211). On the crest of the valley to the S were a series of parallel E–W walls between Via Bonghi and Via Muratori extending along the width of the Porticus-Piscina (Lanciani, FUR pl. 30). These remains are not securely dated, but small traces of opus reticulatum walls were found here (de Vos 1997, 144-45). These walls are shown on our map, since they provided structural support for the platform above; at present, the height difference between the platform and the valley is c. 10 m, but in antiquity it was perhaps c. 20 m (de Vos 1997, 115).As the S limit of the piscina was not ascertained by Lanciani, there is speculation that some of these walls formed the transverse section of a Nilotic T-shaped piscina (de Vos 1997, 135); water was especially important for Isis and Serapis (de Vos LTUR). De Vos questions Lanciani’s representation of an enclosed quadriportico (FUR pl. 30) and proposes a triportico with a vista onto the terrace, hence similar to the Iseum at Pompeii (de Vos 1994, 133). It is very probable that the Porticus-Piscina, together with the area above the substructure found to the E (s.v. *Iseum Metellinum: Substructure), were part of a single Iseum N of the Via Labicana (s.v. *Iseum Metellinum).