A tall building stands on a strong frame of steel beams and columns, a lot like a skeleton. The weight of the whole building pushes down on its columns, and the columns are squeezed by it. Engineers use steel for the frame of most skyscrapers because steel is very strong.

Before steel frames, tall buildings had to be made with thick, heavy masonry walls, and that limited how high they could go. Older stone buildings had thick walls and small windows, because the walls held up the heavy roof. A steel frame changed that. Because the frame carries the weight, the outer wall can have many windows, which stone walls could not.

In 1857 the first passenger elevator was installed in a New York store, and this made buildings taller than four or five stories practical. Elevators let people ride up, so builders could make buildings taller. Elisha Otis showed his safe elevator by having its rope cut while he stood on the platform, and the platform held. His safety brake is a steel spring that grabs a ratchet if the rope breaks.

Steel frames and elevators together made the first skyscraper possible, in Chicago in 1885. The Home Insurance Building there had 10 stories and stood 138 feet tall. The company wanted a fireproof building, so masonry covered the metal frame to protect it from fire. The word skyscraper was used for very tall buildings starting in the 1880s.

An arch pushes outward as well as down. This sideways push is called thrust, and neighboring arches or buttresses must resist it. The Romans used arches, and by about 100 A.D. they had turned the arch into a dome. Gothic cathedral builders used flying buttresses, stone arms on the outside, to carry the roof's push so that the walls could hold big glass windows. The Pantheon in Rome has a dome 142 feet (43 meters) wide.

Everything a building weighs has to end up in the ground. A building has a foundation, the part that goes down into the ground and holds the building up. Where the ground near the surface is too weak, builders use deep foundations that carry the load down to stronger layers. Piles are long, slender columns of steel, concrete or sometimes timber that are put deep into the ground.

Wind is the other big problem. Wind pushes on tall buildings, and they sway a little. Taller buildings face stronger and more complicated wind forces than short ones. Every tall structure sways a little, and engineers watch sway because people on high floors can feel it. Engineers design aerodynamic shapes to calm wind: curved edges, large openings and tapered tops all help a tall building handle wind forces.

Fazlur Khan, who designed the tube systems that shaped modern skyscrapers, was born in 1929 in Dhaka, in what is now Bangladesh, and worked in the United States. In the 1960s Khan moved most beams and columns to the outside walls of a tower, creating a stiff tube that stood up to wind better than a normal frame. His idea was to put the strong parts in the outside walls so that the building acts like a hollow tube.

The core of a tall building holds the elevators, stairs and pipes. It also resists wind and earthquake forces, because its concrete walls, called shear walls, are far stiffer than the outer frame.

The Citicorp Center in New York was a 59-story tower designed by architect Hugh Stubbins, with plans made in 1970. It was completed in 1977. A church stayed on one corner of its site, so the tower had to float above that corner of the church. To lift the tower over the church, the engineer LeMessurier put its support columns at the middle of each side instead of at the corners. Where the supports go is a choice engineers make, and that choice let the tower rise over the church.

A tuned mass damper is a heavy moving weight tied to a building through springs or pistons, and it is commonly used to reduce vibrations in tall buildings. Some towers fight sway with a tuned mass damper. A damper is a heavy weight that is not attached to the building it sits in; as the tower sways, the weight lags behind and pushes against dampers that turn the motion into heat. Taipei 101 has a huge pendulum at the top that weighs 660 tonnes (as of November 2026). It swings the opposite way from the tower, which helps cancel out the swaying.

Words to know

• foundation: ground base
• thrust: sideways push
• skyscraper: very tall building
• damper: motion calmer