The city's major project was organizing and staging the Centennial Exposition, the first World's Fair in the United States, which celebrated the nation's Centennial. Held in Fairmount Park, exhibits included Alexander Graham Bell's telephone and the Corliss Steam Engine. Beginning May 10, 1876, by the end of the Exposition on November 10, more than nine million people had visited the fair. The city undertook construction of a new city hall, designed to match its ambitions. The project was graft-ridden and it took twenty-three years to complete. Upon completion of its tower in 1894, City Hall was the tallest building in Philadelphia, a position it maintained until One Liberty Place surpassed it in 1986.