Legend tells us that Remus had selected the Aventine to live on. It was there that he watched the bird omens, while his brother Romulus stood on the Palatine, each claiming the better results.
The Aventine is noteworthy for its concentration of temples to foreign deities. Until Claudius, it was beyond the pomerium. In "Foreign Cults in Republican Rome: Rethinking the Pomerial Rule" (Memoirs of the American Academy in Rome, Vol. 47 (2002), pp. 1-18), Eric M. Orlin writes:
"Diana (supposedly erected by Servius Tullius, which we may take as an indication of a prerepublican foundation), Mercury (dedicated in 495), Ceres, Liber, and Libera (493), Juno Regina (392), Summanus (c. 278), Vortumnus (c. 264), as well as Minerva, whose temple foundation is not precisely known but must precede the end of the third century."
The Aventine Hill became the home of the plebeians. It was separated from the Palatine by the Circus Maximus. On the Aventine were temples to Diana, Ceres, and Libera. The Armilustrium was there, too. It was used to purify arms used in battle at the end of the military season [Mommsen]. Another significant place on the Aventine was Asinius Pollio's library.