The main office of an organization is its headquarters. The headquarters of your favorite video game company might be in New York.
Companies, clubs, and religious groups all have headquarters, or a central administrative location. Militaries also have headquarters, although the word has a slightly different meaning in that context — military headquarters are where commanders and their staffs live and work. The word has been around since the 1600's, from the "most important or principal" meaning of head and quarters, originally "military dwelling place," and later "lodgings."