THE HISTORY OF SKYSCRAPERS

Great Ziggurat of Babylon

Ancient Skyscrapers

Perhaps the most impressive structure in the ancient Middle East, the Great Ziggurat of Babylon was built over a span of several decades in the Sixth Century BC. Its seven stories, built upon a square foundation, stretched 300 feet into the sky. Some think it was the inspiration for the infamous Tower of Babel in the Book of Genesis. In this illustration, King Nebuchadnezzar, who ruled Babylon from 604 to 561 BC, is seen overlooking his capital.

The Towers of Bologna

The Towers of Bologna

From medieval Bologna to the 21st century's Burj Khalifa, being tallest is mostly about status and wealth rather than practicality. The towers of Bologna are slender, as much as 60 meters (150 feet) tall and were built by the rich for defense and as status symbols. No other site in Europe, or perhaps the world, had so many tall structures crowded together until the coming of skyscrapers in the late 19th century. As many as 180 towers, of many different heights, are thought to have been built in Bologna during the 1100's and slightly later; now there are barely 20.The two most prominent (seen here) are the symbols of the city and have long been known together as the "Two Towers."

First Safety Elevators

First Safety Elevators

In this period illustration, shoppers ride the elevator in the new Lord & Taylor's department store on Broadway in New York City sometime during the 1870's. Around the same time, the first-ever elevator in an office building was also installed in New York. It was designed by Elisha Otis, whose company became synonymous with the new contraption. Elevators revolutionized office buildings, literally turning them upside down. Prior to their invention, the lower floors of a structure were the most valuable rental property because of the difficulty and inconvenience of climbing the stairs. But the elevator made it possible for elite tenants to enjoy the view from the upper floors - and allow buildings to rise higher and higher.

Great Chicago Fire

Great Chicago Fire

In this illustration, Chicago residents flee the terror of the Chicago fire which devastated their city over a three-day period in October 1871. The fire caused nearly $200 million in damage, killed some 300 people and left another 100,000 homeless. Despite this toll, the destruction cleared the way for Chicago to build scores of modern steel-framed office towers and to become one of America's most architecturally striking cities.

The First Skyscraper

The First Skyscraper

Chicago's 10-story Home Insurance Building, built in 1884 and designed by William Jenney, was arguably the first true modern office tower. It was the first building to use structural steel at least partially in its frame, and was the first tall building to be fireproofed both inside and outside. Jenney's ground-breaking structure was torn down in 1931 but its legacy lives on in thousands of steel-framed and fire-proofed buildings around the world.

Tribune Tower Wins Beauty Contest

Tribune Tower Wins Beauty Contest

Pedestrians walk past the ornate entrance and lower floors of Tribune Tower, home of the Chicago Tribune newspaper, which was built in 1925. The 36-story Gothic Revival structure was designed by John Mead Howells and Raymond Hood, who won a contest held by the newspaper company to create "the most beautiful and distinctive office building in the world."

Chrysler Building

Chrysler Building

With its majestic spire, New York City's Chrysler Building is perhaps the most famous Art Deco structure in the world. Built in 1930, the 77-story structure was briefly the tallest building in the world. The sculptures at the top and around the edges are actually inspired by Chrysler hubcaps and hood ornaments. The building's tapering profile is perhaps the best example of "form follows zoning" by taking New York City's setback requirements from 1916 zoning laws - requiring new structures to leave more open space around them - and turning them into an stunning archetype.

Empire State Survives A Hit

Empire State Survives A Hit

This photo shows the spot where a B-25 bomber struck the Empire State Building in July 1945. The aircraft was ferrying servicemen from Massachusetts to New York's La Guardia Airport when pilot William Smith veered disastrously off course in heavy fog. Fourteen people - including Smith - were killed when the bomber hit the skyscraper. The building's 79th floor caught fire, and New York City firefighters bravely rushed up into the building to rescue occupants and put out the blaze. The building's structure and fireproofing both proved strong enough that the New York landmark reopened the following week.

World Trade Center

World Trade Center

The famous twin towers of the World Trade Center were built by the Port Authority in the 1960s as part of an effort to revitalize lower Manhattan. The structure was derided by critics as boring. One wag likened it to a giant pair of filing cabinets, but in time it became a popular New York landmark. The original WTC was the first to use "sky lobbies" where people would change from express to local elevators, a setup inspired by the New York subway system. It also had wide-open, column-free spaces that were ideal for the cubicles then becoming popular in office design. The towers were destroyed in the 2001 terrorist attack that killed more than 2,700 people.

The Sears Tower Bundles The Future

The Sears Tower Bundles The Future

When the Sears Tower, later renamed the Willis Tower, opened in 1973, the 108-story structure became the tallest building in the world and held that title until Malaysia's Petronas Towers claimed the distinction in 1998. This skyscraper was able to achieve that height through a spectacular engineering innovation that introduced the "bundled tube structure" - the Sears Tower is really nine square towers bundled together. It was the start of a revolution in structural design that permitted higher and thinner towers than had ever been built before.

Citicorp Building Skirts Disaster

Citicorp Building Skirts Disaster

The 59-story Citigroup Center building, completed in 1977, had to undergo a costly strength upgrade the following year after it was discovered that the structure was dangerously vulnerable to strong diagonal winds hitting the building's corners. This weakness was a consequence of the placement of the main support columns at the center of the sides rather than on the corners because the building had to float over a church that owned the property. This bold design did win praise for the architect but he subsequently had to suffer the consequences - largely in secret lest panic break out - of experimenting with untested structural elements. If strong dangerous winds had actually toppled the Citicorp building, it is estimated that it might have taken 16 blocks of Manhattan with it.

Petronas Towers Challenge The West

Petronas Towers Challenge The West

Tourists have their picture taken outside the soaring spires of the Petronas Towers in Kuala Lumpur, Malaysia. The 88-story towers, which were completed in the mid-to-late 1990s, were for several years the world's tallest buildings. The project was the harbinger of a global shift in skyscraper building in which Middle Eastern and Asian countries have been racing to erect the tallest and most majestic towers. The two-story sky bridge joining the two towers between the 41st and 42nd floors is not firmly attached to the structures. It is designed to slide back and forth as the towers sway in high winds.

The Gherkin Over London

The Gherkin Over London

One of the more unusual sights in the London skyline is 20 St. Mary Axe, a 41-story office tower opened in 2004, which is nicknamed "The Gherkin" because of its resemblance to a pickle. Though odd-looking, the structure is a prototype for a new generation of innovative, super energy-efficient buildings. Vertical gaps in the building create a natural ventilation system that allows warm air to rise out of the structure. These openings also allow the interior offices to use more natural light to greatly reduce electrical consumption.

Marina Bay Sands, Singapore

Marina Bay Sands, Singapore

Singapore's Marina Bay Sands, a casino and resort complex which opened in 2011, cost an astonishing $8 billion to build. Architect Moshie Safdie's unorthodox design, with its trio of 55-story towers, reportedly was inspired by card decks on gaming tables. The three towers are connected by a giant terrace that supports the world's longest elevated swimming pool. The steel for the pool weighs 191,416 kilos (422,000 pounds) and the water it can hold weighs an additional 1,424,098 kilos (3,139,600 pounds). The towers are constructed to allow movement in the wind - up to 50 centimeters - and longer-term settling in the soil.

Desert Giant Takes The Lead Burj Khalifa

Desert Giant Takes The Lead

Dubai's 160-story Burj Khalifa, which opened in 2010, is by far the world's tallest building. Its startling, rocket ship-like appearance, seen in this photo, seems intended to get attention more than anything else. As architectural critic Paul Goldberger has written, "You don't build this kind of skyscraper to house people... you do it to make sure the world knows who you are." The tall, tapering design is reminiscent of skyscrapers like the Chrysler and Empire State buildings although you could put the two New York skyscrapers one on top of the other and they still would not be as tall.

One World Trade Center, New York

World Trade Rises Again

One World Trade Center (also known as Tower One) rises over Lower Manhattan on the site of the twin towers destroyed in 2001. When completed in 2013, it will have a spire that's precisely 1,776 feet tall (541 meters), making it the third tallest building in the world and the highest in the Western Hemisphere. The new WTC's base is enclosed in thick concrete, steel panels and blast-resistant glass, making it one of the toughest skyscrapers ever built, but security concerns have caused the building's cost to soar, reaching the vicinity of $4 billion.