Walk into any famous city and layers of history begin to emerge. In London, Roman walls sit alongside contemporary architecture. In Rome, ancient treasures like the Colosseum coexist with Renaissance buildings. In New York, skyscrapers from the 1920s and 1930s have been overshadowed by giant glass towers. In "Cities in Layers," six famous global cities will be presented at different stages in their history. A clever cut element allows readers to feel like they are 'flipping through' time.