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By David Nicholson-Cole, The Conversation Updated 1333 GMT (2133 HKT) November 11, 2016 From the legendary Tower of Babel to the iconic Burj Khalifa, humans have always hoped to build to ever greater heights. Over the centuries, we have constructed towering edifices to celebrate our culture, promote our cities -- or simply to show off. Historically, tall structures were the preserve of great rulers, religions and empires. For instance, the Great Pyramids of Giza -- built to house the tomb of Pharaoh Khufu -- once towered over 145 meters high. It was the tallest man-made structure for nearly 4,000 years, before being overtaken by the 160-meter-tall Lincoln Cathedral in the 14th century. Other edifices, such as Tibet's Potala Palace (the traditional home of the Dalai Lama), or the monasteries of Athos were constructed atop mountains or rocky outcrops, to bring them even closer to the heavens. Yet these grand historical efforts are dwarfed by the skyscrapers of the 20th and 21st centuries. London's Shard looms at 310 meters tall at its fractured tip -- but it's made to look small by the world's tallest building, Burj Khalifa, which stands at more than 828 meters. And both these huge buildings will be left in the shadows by the Kingdom Tower in Jeddah, Saudi Arabia. Originally planned by architect Adrian Smith to reach 1,600 meters, the tower is now likely to reach one kilometer high, once it's completed in 2020. So how did we make this great leap upwards? We can trace our answer back in the 1880s, when the first generation of skyscrapers appeared in Chicago and New York. The booming insurance businesses of the mid-19th century were among the first enterprises to exploit the technological advancements, which made tall buildings possible. Constructed in the aftermath of the great fire of 1871, Chicago's Home Insurance building -- completed in 1884 by William Le Baron Jenney -- is widely considered to be the first tall building of the industrial era, at 12 stories high. Changes in urban life also encouraged the change to taller, higher-density facilities. Street trams, subways and elevated rail links provided the means to deliver hundreds of workers to a single urban location, decades before the European motor car appeared on American streets and reshaped urban form away from the city grid. Early office towers filled their city blocks entirely, with buildings enclosing a large light and air-well, as a squared U, O or H shape. This allowed natural light and ventilation within the building, but didn't provide any public spaces. Chicago made a rule of a height limit of 40 meters in 1893, but New York raced ahead with large and tall blocks. In 1915, there was such alarm at the darkening streets that New York introduced "zoning laws." They forced new buildings to step as they went up, in order to bring daylight down to street level. This meant that while the base still filled the city block, the rest of the tower would rise centrally, stepping back every few stories, and it forced the service core to the building's center, leading to the loss of the light well and making mechanical ventilation and artificial lighting essential for human habitation. This was a radical change in the shape of tall buildings, and the second generation of skyscrapers. The developers now had to work out how to maximize the amount of usable floor-space in a city site, before asking an architect to put a wall around it. The mania for profit-driven tall development got out of hand in the late 1920s, however, and culminated in 1931 with the Chrysler and the Empire State buildings. The oversupply of office buildings, the depression of the 1930s and World War II brought an end to the Art Deco boom. There were no more skyscrapers until the 1950s, when the post-war era summoned forth a third generation: the International Style, the buildings of darkened glass and steel-framed boxes, with air conditioning and plaza fronts that we see in so many of the world's cities today. Source: http://edition.cnn.com

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