great hall

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun history, architecture The main room of a palace, castle or large manor house in the Middle Ages, or in a country house of the 16th and early 17th centuries
• noun history, architecture The principal building of a manor or castle compound

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the principal hall in a castle or mansion; can be used for dining or entertainment