Early Italian houses grouped around the atrium, with a small garden, the so-called hortus, at the back.
The classic Roman house, however, was divided into two parts. The first part grouped around the atrium, the second around the peristylium. The peristylium having developed out of the earlier hortus.
The atrium and the peristylium were perfect adaptions to the heat of the Mediterranean. They were open to the sky, letting fresh air in to circulate among the corridors and rooms.
In the atrium a small pool, the impluvium would catch the rainwater, whereas in the peristylium, the rain would water the plants. Further to the impluvium there was an underground tank connected to it which could catch any excess rainwater.
The Roman house is very much a house built for the people of southern Europe. So much so, that when the Romans built their houses in northern Italy or the northern European provinces, they adopted a system of heating, circulating warm air under the floors and along the walls.
