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.
History of the world's tallest buildings
However, though all of these are "structures", some are not "buildings" in the sense of being regularly inhabited or occupied. It is in this sense of being regularly inhabited or occupied that the term "building" is generally understood to mean when determining what is the world's tallest building. The non-profit international organization Council on Tall Buildings and Urban Habitat (CTBUH), which maintains a set of criteria for determining the height of tall buildings, defines a "building" as "(A) structure that is designed for residential, business or manufacturing purposes" and "has floors".