4. The Aon Center

Location: Chicago, IL

Year of Fail: 1974

Built in 1973, the architects placed form above function, neglecting to realize that while stunning, the Carrara marble they used to construct the exterior of The Aon Center was thinner and lighter than more typical building materials. A year after the building went up, one of the marble slabs detached and crashed into the roof of the Prudential Center next door. When an investigation revealed that this might not be a one-time occurrence, the building was resurfaced at a cost of over $80,000,000.