The main room in an early keep was the great hall, a huge open room where meals were eaten, where everyone slept and, quite often, where everyone relieved themselves, too!
One end might have a raised space where lord and lady ate and slept, and which might be curtained off. When the day was done, the tables and benches were packed away and everyone else slept on the floor around the central fire. Later, a fireplace was fitted and some windows even had glass put in them, but by then a new great hall had probably been built in the bailey, like the one shown here.
