The Empire State building was completed in 1931 and was the tallest building in the world for 41 years! The World Trade Center in New York consisted of 2 towers; One World Trade Center and Two World Trade Center. One World Trade Center was the first one to be completed, in 1972. Two World Trade Center was completed in 1973. So as of 1972 the World Trade Center took over the title of the tallest building in the world from the Empire State building.
In 1974 Chicago's Sears Tower was completed. And as of that moment it was generally seen as the tallest building in the world. So the World Trade Center only held the title for 2 years. Sears held on to the title of the tallest building in the world for 22 years, until 1996
In 1996 the Petronas Twin Towers in Kuala Lumpur, Malaysia, were completed. From that moment on a sort of media clash was unleashed. All over the world people debated about the question wich one was the tallest building in the world; Sears or Petronas. You see, Petronas creates its formidable height partly because of its huge spires on top. Sears Tower, however, has the highest occupied floors. So, some people in the press suggested that the Petronas Towers used a trick to obtain the title of the tallest building in the world.
The controversy between Sears Tower and the Petronas towers went on until 2004. In that year the Taipei 101 tower in Taipei, Taiwan was finished. It is now widely known to be the tallest building in the world.
Now the answer to the 'tallest' question seems so easy. Just measure the buildings from bottom to top, and the tallest one gets the title. Question answered, case closed, no more debate needed? Forget it!
But my friends in Canada tell me the famous CN Tower in Toronto is the tallest building in the world?!