AT FIVE THIRTY on a perfect spring evening, there is no one at the Trevi Fountain. The last strips of sunlight slide between apartment buildings and the water gurgles a bright, calming blue. There is only splashing, and pigeons. Not a soul is at the Pantheon, or milling around the Piazza di Spagna, at the base of the Spanish Steps. The Acropolis is absolutely still. A giant neon arrow on the Las Vegas Strip points down to an empty street. Someone has written “Hola” in large letters in the sand in the Canary Islands, but they’ve since gone. Miles of beach stretch long and white and untouched,