"It can resist all the wind that nature can throw at it," is a simple explanation. A skyscraper's construction is made of steel and reinforced concrete, which are exceptionally robust in relation to the area exposed to wind forces. Skyscrapers have withstood winds as high as 300 miles per hour (480 km/hr) without being affected by them. The most destructive force acting on a building is its own weight. This is why buildings have to be designed for safety, especially when they reach up into the sky. The weight of a building increases faster than the square of its height so a very heavy structure is required to be safe at extreme heights. For example, a 40-story building would need to be supported by 80 stories' worth of foundations to be safe. When a strong wind blows against a tall building, it can cause problems for people on the ground who are not used to such conditions. The wind may feel like it's pushing down on the building, but actually it's lifting the top part of the structure off the ground. If enough of these small movements occur over time, then the building will collapse under its own weight. There have been many incidents where this has happened as a result of natural disasters such as hurricanes or earthquakes, but also due to human errors such as cutbacks on maintenance work.