The John Hancock Center is the second tallest skyscraper in Chicago. The building is recongnizable by the "criss-cross design" that gives the building added strength. After people, after 250 years, the structure's leaking roof, finally corrodes a part of the structure necessary for it's strength, the diverging beams of the 85th floor. The beams shear off, and the building has a corner by corner implosion. However it outlasts the more massive Willis Tower.