It is the typical Roman aristocratic dwelling as exemplified at Pompei and Herculaneum. It consisted of rooms grouped round a central hall or atrium (= yard), behind which further rooms were often added, grouped around a colonnaded court or peristyle.

The atrium, a rectangular room with an opening to the sky in the roof, and its adjoining rooms, was a peculiarly Roman element; the peristyle, or patio garden, was Greek or oriental. There were few windows onto the street, since light reached through the atrium or peristyle.