Modern Wonders of the World
Architectural Wonders of
Wall of China
House of Pharos in Alexandria
of Angkor Wat
Warriors of Xian
110-storey skyscraper in
Chicago, USA, is the tallest building in the world. Sears Tower is 443
high, which is over 50 meters taller than the Empire State Building in
City. The tower was originally built as the national headquarters of
People generally agree that the
skyscraper was invented in Chicago, the third largest city in the USA.
a fire destroyed a third of the city, and architects set about
By this time, steel was being mass produced and in 1852, Elisha Otis
invented the lift. New buildings could safely and practically be made
taller. The first high-rise building appeared in the city in 1882. This
Home Insurance Company Building. It was the first building to have a
structure made entirely of steel and iron. It had ten floors – a
than Sears Tower, built 90 years later.
As the demand for land in city
centres grew, people needed to build fast and economically. Skyscrapers
the perfect solution. With new materials and technology, the design of
skyscrapers was gradually improved and perfected. Steel girders were
different ways to make a strong framework. Some buildings were made of
steel tubes designed to withstand the winds that blow around the top
Inside the tubes; individual floors and rooms are rigid so that people
and work safely and comfortably.
It took 2400 workers three
years to build Sears Tower, which was finished in 1973. The tower's
framework is made up of nine square tubes, which form a large square at
base. This rests on concrete, rock-filled shafts that are securely
the solid rock beneath. The nine welded steel tubes rise 50 floors up.
building starts to narrow. Seven tubes continue on up to the 66th
floor. Then five rise on to the 90th floor, leaving just two
to form the top 20 floors. Two television antennae take the building's
height to 520 meters - over half a kilometer. The amount of steel used
the framework was enough to make more than 52,000 cars.
This huge building has over
418,000 square meters of space. That's more than 57 football pitches.
has 104 high-speed lifts, which divide the building into three separate
and make it easier for people to find their way around. The fireproofed
is covered in a skin made of black aluminium and more than 16,000
glass windows. Six automatic window-washing machines clean the whole of
building eight times a year.
1.5 million tourists visit Sears Tower
each year. Two express lifts take them up to the 103rd floor
over a minute. From the tower's Skydeck, visitors have spectacular,
views of Chicago. In the building's lobby there is an enormous 'wall
the famous sculptor Alexander Calder.