Although there has been many controversies about the foundations of the tower due to its faulty construction, the leaning tower became popular all around the world.
However, it's been an interesting fact to know the answer of the most commonly asked question, - "why is the tower of Pisa leaning?"
(I'll try to post the basics as much as I can in relation to the facts provided. 😊)
The leaning tower of Pisa is a free standing bell tower of the Pisa Cathedral well known for its nearly 4-degree lean due to an unstable foundation. It is standing behind the Pisa Cathedral and the Pisa Baptisery. It is considered to be the 3rd oldest structure in the city's Cathedral square.
The tower's height on the high side is 56.67 meters (185.93ft.) from the ground, and 55.86 meters (183.27ft.) on the low side. The wall's width at the base is 2.44m. (8ft. 0.06 in.) and its weight is estimated at 14,500 metric tons. it also has 296/294 steps; - where the 7th floor has 2 fewer steps on the north-facing staircase.
The construction of the tower was built in 3 stages for more than 199 years.
On August 9, 1173, the foundations of the tower were laid with a ground floor of a blind arcade articulated by engaged columns with classical Corinthian capitals.
In 1178, the tower started to sink after the construction had started on the 2nd floor, due to a 3-meter foundation set in an unstable, weak soil, which was considered to be the cause of flaw from the start of construction.
Construction was then stopped for almost a century to allow time for the underlying soil to settle, and at the same time, the people of Pisa were involved actively in various military wars and trade agreements during that time.
In 1272, construction was resumed under the leadership of Giovanni di Simone, - a master builder and architect of the Camposanto. In an effort to compensate for the tilt, they built upper floors with one side taller than the other, - the reason why the tower is curved.
In 1319, the 7th floor was completed, and the bell chamber was finally added in 1372, built by Tommaso di Andrea Pisano, who incorporated gothic styles of the belfry with Romanesque style of the tower. It includes 7 bells, the largest one installed in 1655.
For more than 800 years, they discovered that the tower was actually falling at a rate of 1-2 millimeters per year. Many efforts were done to restore the tower or to keep it from falling over but failed!...some people even worsened it!
The architects and engineers attempted to correct the leaning by making the other stories shorter on the high side but didn't work, and instead kept the tower leaning more. It was also noted later that the cause of the lean was due to the foundation stones being laid on the soft ground consisting of clay, fine sand and shells. Also, the weight of the extra floors caused the edifice to sink further and lean more.
On January 7, 1990, the tower was closed with more than 2 decades of stabilization studies, and as a precaution by the sudden collapse of the Civic Tower of Pavia in 1989.
The bells added were removed to relieve some weight and cables were cinched around the 3rd level and anchored several hundred meters.
In an effort to reduce the tilt, they selected a method by a soil removal of 38 cu. meters (1,342 cu.ft.) from underneath the raised end, in which the tower tilt was reduced by 45 cm. (17.7 inches), returning to its 1838 position.
Between 1993-2001, the structure was stabilized, reducing the tilt to 3.97 degrees. The adding of 870 tons of lead counterweights straightened the tower slightly.
On December 15, 2001, the tower was reopened and was declared stable for at least 300 years. |In May 2008, engineers declared that the tower had been stabilized that it had stopped moving for the first time in its history.
