The oldest temples in this district were those dedicated to Bellona and Apollo.
The earliest worship of Apollo in Rome was connected with the Apollinare, an altar or grove that was situated just west of the Capitolium, between it and the porticus Octaviae. On this spot a temple was built in 429 B.C., which had been vowed the year before in consequence of a plague. This was the only temple of Apollo in Rome until Augustus erected that in the Palatine. It was restored in 32 B.C., and probably again in the years 356-359 A.D. Portions of the foundation wall of opus quadratum have been found beneath the houses on the south side of the piazza Campitelli, and a few fragments of the entablature with reliefs. This temple was frequently used for extra-pomerial sessions of the senate, and it contained many works of art, among them the famous Niobe group, and treasures of various kinds.