In the imperial era the character of the hill changed and it became the seat of numerous aristocratic residences, including the private houses of Trajan and Hadrian before they became emperors and of Lucius Licinius Sura, friend of Trajan who built the private Baths of Licinius Sura. The emperor Vitellius and the Praefectus urbi Lucius Fabius Cilo also lived there at the time of Septimius Severus. The Aventine was also the site of the Baths of Decius, built in 252.