The leaning tower of Pisa in Italy is internationally famous for its unintended til that was a result of an architectural mistake’s what made the historic monument one of the world’s wonders.
The construction of the tower located in Pisa city, known in Italian as “Torre Pendente di Pisa”, started in August 1173 and continued for about 200 years with intermittence due to a series of wars. It was finished in 1399 after many trials to set it straight during construction, while the name of the architect behind the tower remains a mystery.
The Pisa tower was originally constructed as a one of the four buildings that make up the cathedral complex in Pisa called the Field of Miracles or“Campo deiMiracoli”in Italian. They are the cathedral, the baptistery, and the cemetery. Four of them were included in the “Piazza del Duomo”UNESCO World Heritage Site, which was declared in 1987.
The lean and the story behind it:
The Leaning Tower of Pisa was designed to be straight but today it leans more than five meters off perpendicular. The lean was first noticed in 1178 when 3 of the 8 stories were already built due to laying the foundation stones on soft ground of clay, fine sand and shells.
Its engineers tried to correct this by making the remaining stories shorter on the uphill side but in vain. It just kept leaning more and more as the weight of the extra floors caused the building to sink further and lean more. The tower was originally designed to be at height of 60 meters but it is currently at 56.67m at the highest side and 55,86m at the lowest side.
Efforts to reposition it straight:
There were numerous trials to set the Tower straight or at least to keep it from falling. One was taking it apart stone by stone and rebuilding it at a different location. Another, which was quite helpful in stabilizing the tower, was injecting the foundations with cement grouting in the 1920s.
On February 27, 1964, the Italian government requested aid in preventing the tower from toppling so a multinational task force of engineers, mathematicians, and historians gathered started to discuss stabilization methods. They found that the tilt was increasing and many methods were proposed to stabilize the tower, including adding 800 tons of lead to the raised end of the base.
As ideas continued to pour, the leaning tower was closed to the public on January 7, 1990.The bells were removed to relieve some weight, and cables were cinched around the third story. The authorities ordered the apartments and houses in the path of the tower vacated for safety reasons.
The later chosen solution later to prevent the toppling of the tower was to slightly straighten it to a safer position through removing 38 cubic meters of soil from underneath the raised side, they are estimated to weigh 77 metric tons. Due to these efforts the tower was straightened by 45 centimeters returning to its 1838 position.
Later, the tower was reopened to the publics on December 15, 2001 and was declared stable for at least another 300 years. After 7 years, engineers announced the tower stable saying that it stopped leaning in the first time in history and would be stable for at least 200 years.
Visiting the leaning tower of Pisa:
Until years ago, tourists were not allowed to climb the stairs inside the tower but for now it is open again and is one of the most exciting things to do there next to taking a photo beside the tower either holding it up or pushing it.
From over there you can have an immersive view of the town and the ticket price is 18 € on site while reservation are advised if you want to guarantee a spot in queue to climb up the tower. There are 251 steps from the bottom to the top of the Pisa tower.
Note that children under 8 years old aren’t allowed to climb up the tower, while children between 8 and 18 can do so accompanied.