What is Skyscraper?
A skyscraper is a tall, continuously habitable building. There is no official definition nor height above which a building may clearly be classified as a skyscraper. Most cities define the term empirically; even a building of 80 meters may be considered a skyscraper if it protrudes above its built environment and changes the overall skyline.
The word "skyscraper" originally was a nautical term referring to a tall mast or its main sail on a sailing ship. The term was first applied to buildings in the late 19th century as a result of public amazement at the tall buildings being built in Chicago and New York City. The traditional definition of a skyscraper began with the "first skyscraper", a steel-framed ten-storey building. Chicago's now demolished ten-storey steel-framed Home Insurance Building (1885) is generally accepted as the "first skyscraper". The structural definition of the word skyscraper was refined later by architectural historians, based on engineering developments of the 1880s that had enabled construction of tall multi-storey buildings. This definition was based on the steel skeleton—-as opposed to constructions of load-bearing masonry, which passed their practical limit in 1891 with Chicago's Monadnock Building. Philadelphia's City Hall, completed in 1901, still holds claim as the world's tallest load-bearing masonry structure at 167 m. The steel frame developed in stages of increasing self-sufficiency, with several buildings in Chicago and New York advancing the technology that allowed the steel frame to carry a building on its own. Today, however, many of the tallest skyscrapers are built almost entirely with reinforced concrete. Pumps and storage tanks maintain water pressure at the top of skyscrapers.
A loose convention in the United States and Europe now draws the lower limit of a skyscraper at 150 meters. A skyscraper taller than 300 meters may be referred to as supertall. Shorter buildings are still sometimes referred to as skyscrapers if they appear to dominate their surroundings.
The somewhat arbitrary term skyscraper should not be confused with the slightly less arbitrary term highrise, defined by the Emporis Standards Committee as "...a multi-storey structure with at least 12 floors or 35 meters in height." Some structural engineers define a highrise as any vertical construction for which wind is a more significant load factor than earthquake or weight. Note that this criterion fits not only high rises but some other tall structures, such as towers.
The word skyscraper often carries a connotation of pride and achievement. The skyscraper, in name and social function, is a modern expression of the age-old symbol of the world center or axis mundi: a pillar that connects earth to heaven and the four compass directions to one another.
Before the 19th century The Great Pyramid of Giza, circa 2560 BC, was 146 metres tall and its height was unsurpassed until at least the 14th century AD.
The Two Towers of Bologna in the 12th century reached 97.2 metres in height.
The 16th-century city of Shibam consisted entirely of over 500 high-rise tower houses.
Modern skyscrapers are built with materials such as steel, glass, reinforced concrete and granite, and routinely utilize mechanical equipment such as water pumps and elevators. Until the 19th century, buildings of over six stories were rare, as having great numbers of stairs to climb was impractical for inhabitants, and water pressure was usually insufficient to supply running water above 50 m.
The tallest building in ancient times was the Great Pyramid of Giza in ancient Egypt, which was 146 metres tall and was built in the 26th century BC. Its height was not surpassed for thousands of years, possibly until the 14th century AD with the construction of the Lincoln Cathedral (though its height is disputed), which in turn was not surpassed in height until the Washington Monument in 1884. However, being uninhabited buildings, none of these buildings actually complies with the definition of a skyscraper.
High-rise apartment buildings already flourished in antiquity: ancient Roman insulae in Rome and other imperial cities reached up to 10 and more stories, some with more than 200 stairs. Several emperors, beginning with Augustus (r. 30 BC-14 AD), attempted to establish limits of 20-25 m for multi-storey buildings, but met with only limited success. The lower floors were typically occupied by either shops or wealthy families, while the upper stories were rented out to the lower classes. Surviving Oxyrhynchus Papyri indicate that seven-storey buildings even existed in provincial towns, such as in 3rd century AD Hermopolis in Roman Egypt.
The skylines of many important medieval cities had large numbers of high-rise urban towers. Wealthy families built these towers for defensive purposes and as status symbols. The residential Towers of Bologna in the 12th century, for example, numbered between 80 to 100 at a time, the largest of which (known as the "Two Towers") rise to 97.2 metres. In Florence, a law of 1251 decreed that all urban buildings should be reduced to a height of less than 26 m, the regulation immediately put into effect. Even medium-sized towns at the time such as San Gimignano are known to have featured 72 towers up to 51 m height.
The medieval Egyptian city of Fustat housed many high-rise residential buildings, which Al-Muqaddasi in the 10th century described as resembling minarets. Nasir Khusraw in the early 11th century described some of them rising up to 14 stories, with roof gardens on the top floor complete with ox-drawn water wheels for irrigating them. Cairo in the 16th century had high-rise apartment buildings where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants. An early example of a city consisting entirely of high-rise housing is the 16th-century city of Shibam in Yemen. Shibam was made up of over 500 tower houses, each one rising 5 to 11 storeys high, with each floor being an apartment occupied by a single family. The city was built in this way in order to protect it from Bedouin attacks. Shibam still has the tallest mudbrick buildings in the world, with many of them over 100 feet high, and the tallest of them (a minaret) standing at over 175 feet (53 m).
An early modern example of high-rise housing was in 17th-century Edinburgh, Scotland, where a defensive city wall defined the boundaries of the city. Due to the restricted land area available for development, the houses increased in height instead. Buildings of 11 stories were common, and there are records of buildings as high as 14 stories. Many of the stone-built structures can still be seen today in the old town of Edinburgh. The oldest iron framed building in the world is The Flaxmill (also locally known as the "Maltings"), in Shrewsbury, England. Built in 1797, it is seen as the "grandfather of skyscrapers” due to its fireproof combination of cast iron columns and cast iron beams developed into the modern steel frame that made modern skyscrapers possible. Unfortunately, it lies derelict and needs much investment to keep it standing. On 31 March 2005, it was announced that English Heritage would buy the Flaxmill so that it could be redeveloped.
Today, skyscrapers are an increasingly common sight where land is scarce, as in the centres of big cities, because they provide such a high ratio of rentable floor space per unit area of land. But 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.