The leaning tower of Pisa ( torre pendente di Pisa in Italian) is one of the symbols of the center of the Italy.
The tower, emblem of the Tuscan city of Pisa, is a Campanile of Romance style intended to receive the bells of the cathedral from which construction began in 1064.
Characteristics
Located on the Place of the miracles ( Piazza dei Miracoli ) at the center of Pisa, it is high of 54,5 meters, of an external diameter of 15,5 meters at the base, and door of 14 453 tons.This hollow tower, of diameter interns 7,4 meters, is made up of two concentric stone cylinders between which a spiral staircase of 293 steps runs. Between each of the 8 stages, columns of white Marbre of Carrare are used as support, and of many sculptures are visible. The door is decorated with sculptures of animals and other grotesque of Romance style.
The tower is currently tilted of an angle of 5,5° towards the Southern, with the result that the last stage (n°8, that of the bells) exceeds the balance of the foundations of 4,5 meters. This tower measured 4.2 meters of width
- the its of the bells
Caption
The legend says that, the top of this tower, Galileo measured, towards the end of the 16th century, the time of falls of various bodies and could establish that the speed of their fall was the same one for all, and not proportional to their weight as supposed it before Aristote.
History
The construction of the building began the August 9th 1173 and was spread out over two centuries. As of the end of the addition of the third stage towards 1178 the tower had started to lean and construction was stopped during 90 years. Starting from 1272, the four upper floors were thus posed in diagonal to compensate for the slope. Construction then stopped again 1301 with 1350 and it is only in 1372 that the last stage of the bells, of large diameter, was completed. In 1838, a basin was withdrawn at the base of the tower to update the base of the columns which had been inserted under ground.
Measurements of the spacing of the top with the vertical show the progressive slope:
But why does it lean? Built on an Alluvial plain , it started to be inclined very quickly, either because of a defect of foundation, or following a Affaissement of ground due to a rock: the marl.The January 7th 1990, the tower was closed with the public for safety reasons. The monument had been visited then by 18 million people during the 60 previous years.
After expertises, work was started. In September 1995, a cryogenic system to cool the ground proves to make lean the tower even more. In 1998 an internal steel reinforcement was posed and in 1999, 60 m ³ of clay were extracted under the tower and the foundations were reinforced pillars some 15 depth m. This work with height of some 30 M made it possible to bring closer the top with the vertical to 43 cm and to thus stabilize the building for at least a hundred years.
The visits could take again the December 15th 2001, but certain scientists fear that does not curtail the life of this rather fragile construction. However, others affirm that the bell-tower will remain still at least 300 years upright.
Visit
The visit is done by groups of about thirty people. It lasts 30 minutes, without pause, and the guides recall that a sufficient physical shape is necessary to climb almost 300 steps whose slope varies and which the people prone to the Vertige should abstain from. The access on the last floor is rather narrow and can be problematic for the people of strong stoutness. The access is interdict with less than 8 years; the children between 8 and 12 years must be held by the hand during all the visit and the minors of less than 18 years must be accompanied by a responsible adult. All the bags must be left in bottom, but the cameras and cameras are authorized. In 2007, the access was of 15 € per anybody for a 15 minutes visit.
Quotations on the lathe of Pisa
“When the tower of Pisa leans towards the line, it is that it will rain. When it leans towards the left, it is that you arrive by the other end of the street. ” François Cavanna
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