The domus was a single-family house, & insulae were a block or blocks of these
The traditional elite and the very wealthy lived in domus, large single-family... [DOC] [TLE] Insula (building) - Wikipedia [PAR] In Roman architecture, an insula 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).