In 1969, executives of Sears, Roebuck & Co. had the idea to consolidate all of their Chicago area offices into one building.  Being the largest retailer in the world at the time, the building would have to be large enough to meet demands for current employees and future growth.  In April of 1971, construction began on the building project, which featured more than 100 floors.

On this day, May 3rd, in 1973, the Sears Tower is completed in Chicago, Illinois. The building was designed by Skidmore, Owings and Merrill and cost $150 million to construct.  After its completion, the Sears Tower officially became the world’s largest building, measuring 1,451 feet.  Sears’ growth projects were not met in the end and half of the building was vacant for nearly a decade.    In 1982, the addition of two television antennas brought the total heigh of the Sears Tower to 1,707 feet.

By 1992, Sears began to move all of its offices out the tower.  The Sears Tower remained the world’s tallest building until 1998 and it remains to be the tallest building in the United States.  Sears’ naming rights for the tower expired in 2003.  Willis Group Holdings obtained the naming rights in 2009, officially renaming the building as Willis Tower.