After the Social War it became a municipium and under Augustus a colony.
Now in 18 B.C. Augustus carried the Leges Tuliae, which offered inducements to marriage and imposed disabilities upon the celibate.
Augustus gave it back to Naples in exchange for Capri.
In 40 he helped to arrange the peace of Brundisium by which Octavian (Augustus) and Antonius were for a time reconciled.
Paul began the famous Villa Borghese; enlarged the Quirinal and Vatican; completed the nave, facade and portico of St Peter's; erected the Borghese Chapel in Sta Maria Maggiore; and restored the aqueduct of Augustus and Trajan ("Acqua Paolina").