When it opened in Chicago, Illinois in 1973, the Willis Tower was the tallest building in the world, with a height of 1,450 feet. The building was originally (and is still commonly) known as the Sears Tower, as it was built as a new headquarters for Sears, Roebuck & Co.; it was officially renamed after the insurance company Willis Group Holdings, Ltd., in 2009. The building's design, inspired by a pack of cigarettes, consists of a three-by-three set of 'tubes' of varying heights. The tower contains a 103rd-floor 'Skydeck' from which as many as four U.S. states (Illinois, Indiana, Wisconsin, and Michigan) are visible on a clear day, and which also contains several glass balconies that extend out from the building, allowing visitors to look straight down to the street below.