Colleta di Castelbianco, Italy
One important change was that more people lived in small villages for safety, instead of in farmhouses on their own land. Another change was that more people in northern Europe used fireplaces and chimneys to heat their houses and to cook on, instead of an open fire pit in the middle of the room. This made houses a little less smoky than they had been before.
In southern Europe (modern Italy and Spain and southern France), people continued to build their houses out of stone and mudbrick, as they had under Roman rule. To make it easier to live in small villages that people could defend against attackers, the houses became narrow and tall, with little high windows. People heated these houses with charcoal braziers. They had wells or fountains in the middle of the village to get water. None of the houses had bathrooms.
Not so many medieval houses are still around in northern Europe, because people there mainly built in wood. That was because there was plenty of wood around, so it was cheaper to build in wood.