Chicago's iconic Willis Tower, modern skyscraper, sleek glass and steel structure, angular lines, reflective windows, towering high-rise, bustling downtown area, vibrant cityscape, afternoon sun casting long shadows, dramatic clouds drifting across the sky, sharp geometric shapes, urban landscape, concrete sidewalks, pedestrians in business attire walking briskly, taxis and buses whizzing by, American flags waving atop buildings, deep blue and gray tone colors, high-contrast lighting, cinematic composition.