Willis Tower of the four categories in 2004 to become recognized as the tallest building in the world. Taipei 101 surpassed the Petronas Twin Towers in spire height and the Sears Tower in roof height and highest occupied floor. The Sears Tower retained one record: its antenna exceeded Taipei 101's spire in height. In 2008, the Shanghai World Financial Center claimed the records of tallest building by roof and highest occupied floor. On August 12, 2007, the Burj Khalifa in Dubai, United Arab Emirates was reported by its developers to have surpassed the Sears Tower in all height categories. Upon completion, One
Willis Tower the law firms of Schiff Hardin and Seyfarth Shaw. Morgan Stanley plans to move to the building in 2019, and to become the building's fourth-largest tenant by 2020. In 1969, Sears, Roebuck & Co. was the largest retailer in the world, with about 350,000 employees. Sears executives decided to consolidate the thousands of employees in offices distributed throughout the Chicago area into one building on the western edge of Chicago's Loop. Sears asked its outside counsel, Arnstein, Gluck, Weitzenfeld & Minow (now known as Arnstein & Lehr, LLP) to suggest a location. The firm consulted with local and federal authorities