Chicago, architecture walking tour, daytime, sunny, clear blue sky, Willis Tower (Sears Tower), modern skyscraper, glass and steel structure, reflection of city lights, busy street, pedestrians, tourists, cameras, sunglasses, hats, casual clothing, backpacks, maps, enthusiastic gestures, walking, standing, looking up, close-up of faces, 3/4 composition, natural light, warm colors, vibrant atmosphere.