out through a wall or roof. These could be placed against stone walls, instead of taking up the middle of the room, and this allowed smaller rooms to be heated.

Chimneys were invented in northern Europe in the 11th or 12th century and largely fixed the problem of smoke, more reliably venting it outside. They made it possible to give the fireplace a draft, and also made it possible to put fireplaces in multiple rooms in buildings conveniently. They did not come into general use immediately, however, as they were expensive to build and