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The Leaning Tower of Pisa (Italian: Torre di Pisa) is the campanile, or bell tower, for the Italian city of Pisa's cathedral, located in the Campo dei Miracoli. The tower was intended to stand vertically, but began leaning soon after construction started in August 1173. Since then, the Tower of Pisa has become a well-known Italian landmark and is generally recognized around the world.
The height of the tower is 55 metres from the ground. Its weight is estimated at 14,453 tonnes. The current inclination is about ten percent. The tower has 296 steps.
History
The construction of the Tower of Pisa began on August 9, 1173 and continued for two centuries. After the third floor was built in 1178, the tower acquired a lean and construction ceased for a century. In 1272, another four floors were built at an angle to compensate for the tilt. Construction again stopped in 1301 and only in 1372 was the last floor built and the bell installed.
Galileo Galilei is said to have dropped two cannon balls of different masses from this tower to demonstrate their descending speed was independent of their mass. This story is widely considered to be apocryphal.
Benito Mussolini ordered the tower returned to a vertical position so cement was poured into its foundation. The results were unexpected and sank the tower further into the soft soil.
During World War II, the American army destroyed nearly all towers in Pisa due to the potential threat from snipers. The Leaning Tower was scheduled to be blown up as well; fortunately, a last-minute order to retreat prevented the destruction.
On February 27, 1964, the government of Italy requested aid in preventing the tower from toppling. A multilateral task force of engineers, mathematicians and historians was assigned and met on the Azores islands to discuss stabilization methods. After many decades of work on the subject, the tower was closed to the public on January 7, 1990. Recently, the tower was reopened to the public on June 16, 2001 after a decade of corrective reconstruction and stabilization efforts.
See also
References - Shrady, Nicholas (2003). Tilt : A Skewed History of the Tower of Pisa. ISBN 0743229266
External links - Official website (http://torre.duomo.pisa.it), in Italian and English
- Companion site to "Fall of the Leaning Tower" (http://www.pbs.org/wgbh/nova/pisa/) broadcasted by PBS
- "Pisa goes critical" (http://www.rod.beavon.clara.net/pisa.htm), an engineering article on its stabilisation
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