Aon Center

The Aon Center rises as a white monolithic pillar, its square frame wrapped in more than forty thousand slabs of Italian Carrara marble. When it opened in nineteen seventy-three, it stood as the tallest building in the city, but the marble began to warp and fall under Chicago’s temperature swings. By the early nineties, the owners replaced every single slab with white granite. That renovation cost more than the original construction, leaving the tower with its current bright, seam-free finish.