The headquarters of the American diplomatic corps is a forbidding, well-guarded edifice, all modernist, blocky and unfriendly. In stark contrast are the elegant grand diplomatic reception rooms, where Cabinet members and the Secretary of State entertain visiting potentates amid ornate 18th-century American antiques. Tours are by reservation only. Call or go online at least 90 days beforehand to book a spot, and bring photo ID; no kids under 12 years are admitted.
