List of tallest buildings and structures
The tallest artificial structure is Burj Khalifa, a skyscraper in Dubai that reached in height on January 17, 2009. By April 7, 2008 it had been built higher than the KVLY-TV mast in North Dakota, USA. That September it officially surpassed Poland's Warsaw radio mast, which stood from 1974 to 1991, to become the tallest structure ever built. Guyed lattice towers such as these masts had held the world height record since 1954.
Empire State Building
With the destruction of the World Trade Center in the September 11 attacks in 2001, the Empire State Building again became the tallest building in New York City, but was only the second-tallest building in the Americas after the Willis Tower in Chicago. As a result of the attacks, transmissions from nearly all of the city's commercial television and FM radio stations were again broadcast from the Empire State Building. The attacks also led to an increase in security due to persistent terror threats against New York City landmarks.