Basement Level 1 - Unknown
Basement Level 2 - Department of Magical Law Enforcement, Auror Headquarters, Wizengamot Administration Services
Basement Level 3 - Department of Magical Accidents and Catastrophes, Accidental Magic Reversal Squad, Obliviator Headquarters, Muggle-Worthy Excuse Committee
Basement Level 4 - Department for the Regulation and Control of Magical Creatures, Beast Divisions, Being Divisions, Spirit Divisions
Basement Level 5 - Department of International Magical Cooperation, International Magical Trading Standards Body, International Magical Office of Law, International Confederation of Wizards, British Seats
Basement Level 6 - Department of Magical Transport, Floo Network Authority, Broom Regulatory Control, Portkey Office, Apparition Test Centre
Basement Level 7 - Department of Magical Games and Sports, British and Irish Quidditch Headquarters, Official Gobstones Club, Ludicrous Patents Office
Basement Level 8 - The Atrium, The Reception Area, Fountain of Magical Brethren, Security Desk, Lifts
Basement Level 9 - Department of Mysteries, Hall of Prophecies, The Death Chamber
Basement Level 10 - Courtrooms