Introduction to the John Hancock Center: The John Hancock Center, commonly known as "Big John", is about 344 meters high and has 100 floors. When it was completed in 1969, It is the world's tallest building outside New York. There is an observation deck on the 94th floor of the building, a restaurant on the 95th floor with views of Chicago and Lake Michigan, and the highest indoor swimming pool in the United States on the 44th floor.