Building the Leaning tower of Pisa
It’s a rare thing that a building would be so celebrated for being so crooked. When the leaning tower of Pisa was first built, however, it wasn’t leaning at all. Today, this tower is a magnet for tourists and travellers but when it was built in 1173, it served a much different purpose. This is the story behind the leaning tower of Pisa and why it leans in the first place.
What is the Leaning Tower of Pisa?
The tower was not built to become the ‘leaning tower of Pisa”. It was, in fact, built to be a bell tower for the cathedral complex in the city of Pisa, Italy. Many older cathedrals have freestanding bell towers built separate from the main building to allow for larger bells. With construction being done entirely by hand, large sound waves and vibrations would have distrubed the main building if they were built together. This way, bells could toll uninhibitedly and the church and church-goers would not be disturbed.
Pisa at the time was a small and simple town but was a bustling seaport for the country of Italy. As the city began to grow in the 1100s, so did the need for a religious center. The entire cathedral complex in which the bell tower stands was built as a display of strength and importance for the city.
What is the Tower Built Of?
No one knows the architect responsible for the initial design of the building. The tower is mainly built of white marble but limestone was also used in construction. Many think that the mixed material use is what saved the building from falling completely. Limestone is much more flexible than marble, giving it the ability to withstand the internal compression caused when the tower began to lean.
Leaning Tower of Pisa Construction
The marble and limestone used in construction would have been mined, harvested, transported, cut, heaved and settled into place all by hand.
Construction of the tower began in 1173. In the first few years, the first floor and foundations were laid for the tower. According to written documents, the foundation of the tower was completed a year after construction began in 1174. By 1178 the second floor of the tower was well underway and the tower was already beginning to sink.
There are a few factors responsible for this sinking. The foundation was only 3 meters thick and the subsoil it was set into was weak and unstable. The design was slightly flawed right from the beginning. The entire project would have been doomed if it wasn’t forced to halt by a war that began between the Republic of Pisa and other areas within Italy.
Construction came to a halt for almost 100 years. During this time, the soil was able to settle under the new weight of the marble. In 1264, master builder Giovanni di Simone - architect for other parts of the same Cathedral Square in Pisa - took 23 workers up the side of the mountains of Pisa to cut away more marble. Construction resumed in 1272.
The building, at this point, was already leaning. In an effort to compensate for the tilt, engineers began to build the upper floors with one side taller than the other to distribute weight. The tower is curved because of this design feature.
Construction of the tower was once again paused in 1284 during another Italian battle.
The seventh floor was finally finished in 1319. The top bell chamber followed more than 50 years later in 1372. 7 bells in total were installed in the tower.
Straightening the Tower
There have been many attempts to straighten the tower of Pisa. The goal was never to straighten it completely because the leaning tower was a major tourist attraction for the city. Instead, preventing further collapse and providing stability to the tower was the goal.
In January 1990, the bells were removed to pull some weight from the tower. In 1993, counterweights were added to the tower which did straighten it slightly. Soil was removed from under the foundation raised-side of the tower to level it slightly. This particular project reduced the tilt by 17.5 inches. 70 tons of soil was removed in total and the tower was declared to be stable for another 300 years.
Facts About the Leaning Tower of Pisa
The leaning tower of Pisa weighs about 14,700 tons, and sits at a 3.99-degree angle.There are 294 steps in the tower that take you up 7 floors to the top. There used to be 7 bells in the tower, all tuned to the musical scale. The tower should be 60 meters tall but because of the slant, it sits about 56.67M on the highest side and 55.86M on the lowest side. More than 5 million tourists travel to visit the tower every year.
The Leaning Tower of Pisa
The engineers and construction workers of the tower did not tear it down once they saw it was tilting. They pushed forward, adapted their designs and proceeded to build one of the most popular imperfect buildings in the world. Their ingenuity and creativity was rewarded almost 800 years later when the tower was declared a UNESCO World Heritage Site.
