What was the tallest building in the world when it was completed in 1974?

The Willis Tower, originally known as the Sears Tower, was the tallest building in the world upon its completion in 1974, standing at a height of 1,450 feet (442 meters). Designed by architect Bruce Graham and structural engineer Fazlur Rahman Khan, the Willis Tower was a significant achievement in architectural engineering and became an iconic symbol of Chicago's skyline. Its innovative design includes a bundled tube structure, which allowed for greater height and stability compared to traditional skyscraper designs. This architectural approach influenced many subsequent tall buildings globally.

In contrast, the Empire State Building, completed in 1931, held the title of the world’s tallest building prior to the Willis Tower, while the Burj Khalifa, completed much later in 2010, currently holds the title for tallest building in the world today. One World Trade Center, completed in 2013, is another notable skyscraper but was completed many years after the Willis Tower. The distinction of the Willis Tower as the tallest building of its time significantly marked Chicago's architectural history and set a benchmark for future skyscrapers.