Leaning Tower of Pisa-
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| leaning tower of Pisa |
The world-famous Leaning Tower of Pisa sits in
the Campo dei Miracoli in the Italian city of Pisa.The Leaning Tower
of Pisa or Pisa tower is one of
the most architectural structures from Medieval Europe that
is famous for the settling of its foundations, which caused it to lean 5.5
degrees (about 15 feet [4.5 meters]) from the perpendicular in the late 20th century
. Later extensive work has been done to straighten the tower and
it was ultimately reduced to less than 4.0 degrees. Pisa
tower is the third oldest building on (cathedral square), the
Cathedral and It is located in the Italian town of Pisa, one of the most
visited European cities. The Leaning Tower of Pisa is the piazza’s
crowning glory. it is a miracle of medieval engineering, probably the
tallest bell towers in Europe. The construction of Tower of Pisa began in
August 1173 and it is constructed of white marble and
designed has a circular bell tower. The tower has eight stories,
including the chamber for the bells.
The construction of bell tower begun in
August 14, 1173 across 199 years.The tower site sat on soft ground
composed mostly of clay, fine sand, and shells (the city sits between the
Arno and the Serchio rivers) The tower began to sink after
construction had progressed to the second floor in 1178. This was due to a mere
three-metre foundation, set in weak, unstable subsoil, a design that was flawed from the beginning.
Construction was subsequently halted for almost a century, because the Republic of Pisa was almost continually engaged in battles with Genoa, Lucca,
and Florence. This allowed time for the underlying soil to settle.
Otherwise, the tower would almost certainly have toppled.
After the 100 year hiatus, Giovanni di
Simone stepped forward in
1272. In an effort to compensate for the tilt the engineers built
upper floors with one side taller than the other.He actually managed to cause
the tower to lean over more when he tried to compensate for the original lean
by making one side of the upper floors taller than the other. Construction
was halted again in 1284, when the Pisans were defeated by the Genoans in the Battle of Meloria
The seventh floor was completed in 1319. The
bell-chamber was finally added in 1372.It was built by Tommaso di Andrea Pisano.
In 1838 Alessandro Della Gherardesca, an established
architect, dug a pathway near the base of the tower so that people could see
the intricately crafted base. The tower began to lean even more as a result,
likely due to the decreased amount of support available within the soil.
German troops may have used the tower as a
lookout during World War II. When the United States entered the war, the
military planned to destroy all possible sniper locations in Italy, including
the tower in Pisa. Soldiers had to retreat before they could level the tower,
however.
Numerous efforts have been made to restore the
tower to a vertical orientation or at least keep it from falling over. Most of
these efforts failed; some worsened the tilt.
In 1964, Italy asked help to prevent the Leaning
Tower from toppling. They wanted to keep the lean though, because of its
importance for Pisa's tourism. A team of engineers and historians came together
on the Azores to discuss the problem. As a temporary measure, a leaden
counterweight (800 tonnes) was installed.
In 1987, the Leaning Tower of Pisa was declared a Unesco World
Heritage Site, along with the
entire Piazza Del Duomo.
In 1990, the Leaning Tower was closed to
relieve some weight, and cables were cinched around the third level and
anchored several hundred meters away. Its lean is now only about 4 degrees
(prior to the all the restoration attempts, the lean was 5.5 degrees), or about
13 feet past perfectly vertical.
After a decade of corrective reconstruction
and stabilization efforts, the tower was reopened to the public on December 15,
2001, and was declared stable for at least another 300 years.
In May 2008, after the removal of another 70
metric tons (77 short tons) of ground, engineers announced that the Tower had
been stabilized such that it had stopped moving for the first time in its
history. They stated it would be stable for at least 200 years.
Reopened in 2001 for tourists, the leaning
tower of Pisa is finally sturdy and safe. Naturally, climbing to the top of the
tower has become the most popular tourist activity within reason, and for good
reason: with a history as deep and as wrought with unfortunate circumstance as
this one, it's hard not to get excited about.
Unfortunately, even today the great mass
continues to sink very slowly. It is a question of about 1 mm. every year. Since nobody can
state with mathematical security that this sinking will continue in the future at the present yearly rate,
without its ceasing, remedies by means of adequate measures, based on
scientific studies and projects, are under consideration. In the meantime supervision
with instruments of
very high precision is continuously being carried out.
