insulae

Insulae: In Roman architecture, an insula (Latin for "island," plural insulae) was a kind of apartment building that housed most of the urban citizen population of ancient Rome, including ordinary people of lower- or middle-class status (the plebs) and all but the wealthiest from the upper-middle class (the equites).  Remains of the top floors of an insula near the Capitolium and the Aracoeli in Rome.