Take a minute to imagine that you have traveled with your family to Italy. You visit a popular tourist spot to check out one of the most famous buildings in the world: the leaning Tower of Pisa. As you approach the tower, you can see that it is leaning over at a strange tilt. How is this tower even standing? It has white pillars and arches. It leans at an angle that is scary, but you can see that it is held up by large metal wires pulling against its weight. Your family decides that they are going to go inside to explore. It sounds a little risky to go inside a leaning tower. Will you go inside too?
The Leaning Tower of Pisa is one of the most famous buildings in the world. It is a freestanding bell tower in the cathedral of the Italian city of Pisa. A cathedral means a church that has a section where a religious leader, a bishop, lives inside. The tower is known around the world for its strong lean. The tower leans at an angle of four-degrees. The lean is due to a foundation that is not stable. This means that the base of the tower that holds the tower up is likely to fall.
The Tower of Pisa is 183 feet from the ground on the low side and 186 feet on the high side. It has 295 steps to the top level.
The Tower first began to lean during the time it was built in the 12th century. This happened because the ground that the Tower was built on was soft and could not properly support the weight of the huge tower. Throughout the building of the tower, the leaning only got worse. Oops! And it continued to lean more over the next few hundred years. By 1990, the tilt had reached 5 ½ degrees! This was so far over that the Italian government decided to add extra support beams to help stabilize the tower. Their work was successful and after 8 years of extra work the tilt of the building was reduced to 4 degrees.
There is some mystery around who designed the Leaning Tower of Pisa. For many years, people thought that the architect was a man named Bonanno Pisano. This was based on a piece of metal found in the earth at the base of the tower. But later scientists concluded that a different man named Diotisalvi was that actual architect and that Pisano likely just made the door frame. This was due to the fact that the tower is very similar to at least two other buildings that Diotisalvi designed in Pisa.
The Tower of Pisa was built in three stages over almost 200 years. In the year 1172, a woman named Donna Berta di Bernardo inherited a large sum of money from her husband. She gave some of this money to the local Opera house in Pisa and she used the rest towards buying a few stones that are still part of the base of the bell tower.
One year later, the government had enough money to hire a crew of workers to continue to build the tower. The government had more money than in recent years due to the fact that the army had successfully taken over some additional areas. The crews started by building the foundations of the tower. Later that year, they laid the ground floor of the tower with white marble. This ground floor has a “blind arcade”. This means that the bottom had columns with classical looking arches but the other side of the arches have no actual openings. Instead, it is just a hard surface of a wall with arches that are decorative, or there to make it look nice.
The arches also aren’t “load-bearing”. This means that they do not support the weight of the structure.
About 400 years later, a man named Giorgio Vasari wrote that Guglielma together with sculptor Bonanno laid the foundation, or base, of the bell tower in the tower of Pisa.
The tower began to sink after construction had progressed to the second floor in 1178. The reason was because the foundation was not built to be high enough. It was only three-metres high, which was very low for a tower of that height.
Unfortunately, the tower was set in weak, unstable soil or dirt. This was a problem that was there right from the beginning. Because the tower started to sink, the people who were building the tower stopped construction. The tower then sat there for almost 100 years with nothing being done. The country that the tower was in was called the Republic of Pisa. The Republic was almost constantly battling with the neighbouring countries of Genoa, Lucca and Florence.
The 100 years that the tower sat there was actually a good thing. This allowed time for the soil underneath the tower to settle, or become more stable. If the original construction crew had carried on building the tower, the tower would have almost definitely fallen over.
In the year 1233, a father and son started to do further construction work on the tower to try to finish it. They eventually had to pass the project on to another builder and then yet another took over.
In 1264, the tower construction had finally moved along far enough that the main architect at the time, hired 23 workers to go into the mountains close to Pisa and cut marble. After the marble was cut out of the mountain, they used it on the tower. In order to compensate, or counter-balance, for the tilt, the designers build the upper floors of the tower with one side taller than the other. For this reason, the tower is actually curved today.
The seventh floor was finished in 1319 and then the bell-chamber was finally added in the year 1372. The bell-chamber, or room holding the bell, was built by a man named Tommaso di Andrea Pisano. He used Gothic elements and a Romanesque style of the tower. These are different historic styles of buildings that were popular at different times in Europe’s history. There are seven bells in the bell-chamber, one for each note of the musical major scale.
After the tower of Pisa was finished, the tower was admired by many people and has had some famous visitors. A famous astronomer _______ dropped cannonballs off of the tower to show the law of free fall, a famous law in physics. Physics is the study of matter and motion, or things and movement.
During World War 2, the Allies, Americans and English, thought that the Germans were using the tower of Pisa as a watch post. A U.S. Army sergeant was sent to find out if German troops were in the tower. He was so impressed by the beauty of the tower, that even though he found that there were Germans in there he held back on ordering an air attack to save the tower from being destroyed.
There have been many attempts to restore the tower to a straight, standing, position or at least keep it from falling over. Unfortunately, most of these efforts failed. And some of these attempts even made the tower worse.
In 1964, the Italian government raised money to restore the tower again and stop it from falling over. The government wanted it to become more stable, but it still wanted the tower to have a tilt. They realized that the tilt was what made it famous! It helped attract tourists, or visitors from other places, to visit Pisa, so why fix it?
The Tower was closed to visitors in January 1990 due to the collapse of another tower nearby. The collapse scared the Italian government that the same things might happen to the tower of Pisa. They removed the bells to take some of the weight out of the towers. They also cinched cables around the third level of the tower and anchored the cables hundreds of metres away. People who lived in home nearby were told to leave to make sure they wouldn’t be hurt if the tower fell over.
In 1993, the Italian government added almost 900 tonnes of lead counterweights, or weights on the other side of the tower to counter-balance the weight of the leaning side. This helped straighten the tower a bit. They also removed soil underneath the raised side of the tower to help prevent the collapse of the tower. This helped to make the tilt of the tower a safer angle. This method worked! The tower’s tilt was reduced by almost 18 inches, returning to its 1838 position.
Finally, after 10 years of work to rebuild the tower and make it more stable, the tower was re-opened to the public in December 2001. The government declared that it was now stable for at least another 200 years.
Would you like to visit the leaning tower of Pisa one day? If you do visit, would you brave enough to go inside?