Piranesi, Juvarra, and the Triumphal Bridge tradition

Perhaps more influential than Ligorio's map in establishing the reality of the Pons and Via Triumphalis in the Renaissance imagination was Onofrio Panvinio's map of 1565 (Fig. 9). (47) Bearing the same name as Ligorio's large perspective plan, it cut Ligorio's speculations down to size, and it may have been more acceptable to those who distrusted the element of fantasy in Ligorio's work. Unlike Ligorio, Panvinio was interested in routes. Like Ligorio, he walled the Tiber from the Mausoleum of Hadrian to the point where it meets the Janiculum, just past the bridge. Although he calls the bridge "Pons Vaticanus," he is still thinking of the Via Triumphalis, since there is a "P. [orta] et V. [ia] Triumphalis" in the wall on the Vatican bank, corresponding to Ligorio's Porta Aurelia. There is no arch on the Campus Martius side of the bridge. Like Ligorio, Panvinio was uncertain about the route of the Via Triumphalis across the Ager Vaticanus. The road splits into three. The main branch, and the one retaining the n ame, crosses the Vatican hill past the end of the Circus Gaii et Neronis, which is placed here instead of in the valley, and joins the Via Aurelia on the far side. The Via Aurelia is thus for Panvinio the more northerly route, skirting the back of the Mons Vaticanus and running slightly to the north of the Meta Romuli, a Roman pyramid destroyed in 1499 in making the Via Alessandria, (48) to enter its gate close beside the Mausoleum of Hadrian. In the Campus Martius, the Via Aurelia passes through the Arch of Arcadius and Honorius to rejoin the Via Triumphalis near the Villa Publica, here located on Monte Giordano, and from there goes past the Theater of Pompey.

How Panvinio understood the Via Triumphalis to have functioned is made clear in the series of engravings depicting a Roman triumph attached to the publisher Gian Giacomo de Rossi's 1649 reissue of Etienne Duperac's 11574 map of ancient Rome that reflect Panvinio's ideas. (49) This triumph is based on those of L. Paulus, P. Africanus Aemilianus, Pompey, Julius Caesar, Augustus, Vespasian, Trajan, and other Roman emperors. (50) It is shown starting at the Porta Triumphalis (last panel), understood to be located in the walls on the Vatican bank, with the adlocutio (address) of the emperor and a sacrifice taking place outside the walls. (51) There is no indication of the Pons Vaticanus, even though this was marked on Panvinio's map, implying that the bridge had no significance other than as the means by which the Via Triumphalis was carried over the river. The triumph culminates on the Capitol at the temple of Jupiter Capitolinus (first panel). Like all the maps of this period, it does not show a Porta Triumphali s at the foot of the Capitol. (52)

Although employing a different framework, Duperac in his small map of 1573 describes the same arrangement as Panvinio's, but with greater clarity. (53) His large map of 1574 (Fig. 10), although based on Ligorio's Imago urbis, draws on other sources, including the first fragments of the Severan marble map of Rome, (54) which began to emerge starting in 1562, (55) and retains Panvinio's "Pons Vaticanus" appellation, while clarifying greatly Ligorio's treatment of the routes. The Via Triumphalis is for the first time clearly shown as a road crossing the Campus Martius. The Arch of Arcadius and Honorius is again located on the road from the Pons Aemilius, at a point shortly before it meets the Via Triumphalis. The Via Triumphalis continues past the Theaters of Pompey and Marcellus before losing its identity in the Forum Olitorium, which is here located between the Theater of Marcellus and the Capitol. Like Ligorio, Duperac showed an arch with a pediment on the Campus Martius end of the bridge, but the gate in the wall corresponding to Ligorio's Porta Aurelia is now apparently the Porta Triumphalis, following Panvinio, since the inscription along the route passing through it reads ET PORTA ... VIA TRIUMPHALIS. The space between the walls and the Tiber implied in Ligorio is here made explicit, clearly depicting the Porta Triumphalis as structurally distinct from the bridge. The pornerium is indicated as being an open space on the Vatican side of the walls. In short, Duperac modeled his map on Ligorio but followed Panvinio in locating the Pons Tniumphalis in the wall on the Vatican bank, perhaps because of the nexus between the Porta Triumphalis and the pomerium.