Originally built as the headquarters for the Standard Oil Company, it was renamed the Amoco Building after Standard Oil changed its name. The building received a new name after Amoco moved out and Aon Insurance became the largest tenant. At 1,136 feet, the 83 story Aon Center is the 2nd tallest building in Chicago after the Sears Tower. It's brilliant white granite facade was installed after the original marble cladding started to crack and fall apart. The re-facing of the tower cost more than it took to build the center in the first place.
Designed by architect Edward Stone, the Aon Center is dominated by the vertical. It bears a striking resemblance to New York's World Trade Center, and is indeed very similar structurally. However, the Aon Center's closest relative is Toronto's First Canadian Place, which was also designed by Stone.
1) Cut-out main tower (#1). Fold as a normal box, but make sure to W-fold the corners.
2) Cut out and fold the elevator box (#6) and glue to roof of #1
3) Cut out #2 and both #3's. Be careful when folding the sides of #2. Attach both #3's to the front of #2.
4) Attach main tower (1 & 6) to plaza/base (#5)
5) Attach upper ground level (2 & 3) to base.
6) Attach #4 to the front of #5