Two thousand years and its dome still the greatest unreinforced concrete ever: the Pantheon — the open oculus (9m) its only light, sun circling the walls as a sundial, entering rain swallowed by cleverly pierced marble floors in pure Roman wit. The token ticket queue moves fast with early morning calmest; stand directly beneath the eye and look up — the moment you came for; its square and famous Tazza d'Oro coffee beside close the Roman rite.