Most of the structures are television broadcasting masts . There are also the taller tower-type structures ( like the CN Tower ) and the taller high rise buildings ( like the Sears Tower ) . The tallest is the Burj Khalifa skyscraper at 828 m , but most of the structures listed are television broadcasting masts , followed by a mix of the taller tower-type structures ( e.g. the CN Tower ) and the taller high-rise buildings ( like Willis Tower ) .