Designing massive skyscrapers like "Burj Khalifa" (800mts), "Taipei 101" (500mts) is a true challenge for engineers, this buildings need to be prepare for natural disasters like hurriacanes tsunamis, earthquakes ande the wildest weather. They need to be able to resist wind forces of move than 100mph at the top of the building. If the building doesnt move at the top the structure might be damaged beacause of the wind pressure, for the word "move" doesn't mean the building goes to fall down but the people at the top will start to feel a little queasy.
Some buildings are designed with special techniques to reduce the wind pressure like "Chinas Shangai Financial Center" (490mts) which was built with a hole at the top of the structure. But not all the problems are outside they also are inside and one of them is providing water and clean air in all the rooms from the bottom to the top and that is not a easy task for the engineers and it goes harder when the windows dont open, for that tasks exists mechanical areas who are in charge to swap air inside with circulating air outside. Also you dont want to hear the pipes of water moving through the building so the engineers need to make sure its sound-proofed as well.