Willis Tower
Black bands appear on the tower around the 29th–32nd, 64th–65th, 88th–89th, and 104th–108th floors. These give the building's environmental support systems and hide its belted trusses. Even though adding a fire sprinkler system was not forced, the building was built with one from the beginning. There are around 40,000 sprinkler heads in the building. They cost $4 million.