3. It Was the Seat of British Intelligence’s American Operations During World War II

International Building North, a structure in the original complex, was where British Intelligence set up their base of operations throughought World War II, beginning with Hitler’s occupation of Poland. The building’s room 3603 was additionally used as the headquarters of Allied Intelligence, and functioned as the office of Allen Welsh Dulles, who would become the civilian director of the yet-to-be-formed Central Intelligence Agency.