BRANDCAST MAKES IT SIMPLE
High-rise buildings became possible with the invention of the elevator and less expensive, more abundant building materials. The materials used for high-rise buildings are reinforced concrete and steel. Most North American skyscrapers have a steel frame. There is no clear difference between a tower and a skyscraper, although a building with forty or more stories and taller than 150m (490ft) is generally considered a skyscraper.