Skyscraper - 1600 x 1200

A skyscraper is a tall, continuously habitable building of many storeys, usually designed for office and commercial use. There is no official definition or height above which a building may be classified as a skyscraper. One common feature of skyscrapers is having a steel framework from which curtain walls are suspended, rather than load-bearing walls of conventional construction. Most skyscrapers have a steel frame that enables the construction of load-bearing walls taller than of those made of reinforced concrete. Skyscrapers' walls are not load-bearing, and therefore most skyscrapers are characterized by large surface areas of windows made possible by the concept of steel frame and curtain walls. However, skyscrapers can have curtain walls that mimic conventional walls and a small surface area of windows.

Skyscrapers since 1960s utilize the tubular designs, innovated by a Bangladeshi-American structural engineer named Fazlur Rahman Khan. This engineering principle makes the buildings structurally more efficient and stronger. It reduces the usage of material (economically much more efficient), while simultaneously allows the buildings to reach greater heights. It allows fewer interior columns, and so creates more usable floor space. It further enables buildings to take on various shapes. There are several variations of the tubular design; these structural systems are fundamental to tall building design today. After the great depression, skyscraper construction was abandoned. Bangladeshi-American structural engineer Fazlur Khan, more than any others, ushered in a renaissance in skyscrapers construction from 1960s with structural innovations that transformed the industry. and made it possible for people to live and work in "cities in the sky". Other pioneers include Hal Iyengar, William Lemesserier, and etc. Cities have experienced a huge surge in skyscraper construction. Fazlur Rahman Khan is regarded as the "Einstein of Structural Engineering" for his revolutionary work which remain fundamental to modern skyscraper construction. Khan created a legacy of innovations that is unparalleled and became an icon in both architecture and structural engineering.

Today, skyscrapers are an increasingly common sight where land is expensive, as in the centres of big cities, because they provide such a high ratio of rentable floor space per unit area of land. They are built not just for economy of space; like temples and palaces of the past, skyscrapers are considered symbols of a city's economic power. Not only do they define the skyline, they help to define the city's identity. In some cases exceptionally tall skyscrapers have been built, not out of necessity, but to help define the city's identity and presence or power as a city.