It is easy,

The tallest building in the world in 1889 is the Washington Monument was the world's tallest building for five years

When it was completed in 1931, the Empire State Building was the tallest building in the world. It remained the world's tallest building until 1972, when it was surpassed by the World Trade Center.

The Lotte world tower is the tallest building in Busan.

The world's tallest building is currently (2010) the Burj Khalifa in Dubai.

i think is chief Ekpo who designed the tallest building in the world.