<p>This quadriportico, located along the NE side of the *Circus Flaminius between the *Porticus Octaviae and the *Petronia Amnis, enclosed the Temple of Hercules Musarum (e.g., Pliny, <i>NH</i> 35.66: <i>in Philippi porticibus</i>; index no. 31 a). M. Fulvius Nobilior may have built it between 187 and 179 B.C. (Eumen., <i>Pan</i>. 5.7.3; Coarelli 466-67), yet according to Ovid (<i>Fast</i>. 6.801-2) and Suetonius (<i>Aug</i>. 29.5), L. Marcius Philippus, who triumphed in 34 or 33 B.C., restored the Temple of Hercules Musarum and built the portico around it. Near the temple was the formal gathering place of the <i>collegium poetarum</i> (Val. Max. 3.7.11; Pliny, <i>NH</i> 34.19), which may have been established in Rome during the period in which the temple was built (Coarelli 472, Tamm).</p> <p>A fragment of the Severan Marble Plan (Rodríguez Almeida, <i>Forma</i> pl. 23, frag. 31) depicts part of the enclosure; its S façade is a direct continuation of the S wall of the *Porticus Octaviae. The outer perimeter of the <i>porticus</i> may have consisted of a wall with only one row of columns, since Castagnoli (1983, 99) interprets the second row of dots on the Severan Marble Plan as trees (contra, Richardson 359, who advances a theory of a double colonnade). It seems also that, unlike in the Porticus Octaviae, the temple was completely enclosed by the colonnade and lacked a monumental entrance (Viscogliosi 146). Inside the portico a S-facing podium (<i>c</i>. 48 x 21 m, H. 3.5 m; Coarelli 476) with an <i>exedra</i> (diam. 11 m) on its N side is shown. Depicted on the long sides of the podium are 12 niches (W. 3.5 m), perhaps for placement of the <i>fasti</i> (Macrob., <i>Sat</i>. 1.12.16; Coarelli 480-82). Represented on top of the podium are two circular structures, identified respectively as the temple and the altar of Hercules Musarum. Just N of the podium is a row of 9 rectangular bases, perhaps for statues of the Muses (Coarelli 483), since at some point the <i>aedicula</i> of the *Camenae was moved from the Temple of *Honos and Virtus to the <i>aedes Herculis et Musarum</i> (Servius, <i>ad Aen</i>. 1.8). If such an identification corresponds to reality, then the <i>exedra</i> at the back of the podium must be the auditorium where the <i>collegium poetarum</i> gathered (Coarelli 483-84). Public facilities, perhaps toilets, belonging to the *Theater of Balbus may have been located N of the portico (Coarelli 475).</p> <p>The Severan Marble Plan must have depicted the original layout of the portico, since it corresponds with the fragmentary remains of its early Republican walls in cappellaccio tufa (Castagnoli 1983, 100; Gianfrotta). The difference in elevation (<i>c</i>. 3 m) between the <i>porticus</i> and the area around it was probably purposeful and intended to avoid damage caused by inundation (as in the *Porticus Octaviae and Temple of *Apollo Sosianus; Castagnoli 1983, 100).</p>