Leaning Tower of Pisa (피사의 사탑, Torre di Pisa)

The Leaning Tower of Pisa, located in the city of Pisa in the Tuscany region of Italy, is one of the most famous leaning towers in the world. As an annex building of Pisa Cathedral, its construction began in 1173, but it started to lean during the construction process and was completed in 1372. How can this tower, which remains leaning to this day, stand without collapsing? In this article, we will explore the history, structure, cause of the lean, and preservation methods of the Leaning Tower of Pisa.

History of the Leaning Tower of Pisa

The Leaning Tower of Pisa is the bell tower of Pisa Cathedral, built in the Romanesque style with an 8-story structure. The tower is 55.86 meters tall, with 297 steps. It weighs approximately 14,453 tons, and the average stress exerted on the ground is 50.7tf/m2.

Construction of the Leaning Tower of Pisa began on August 9, 1173. At that time, Pisa was a significant port city in the Mediterranean Sea, with abundant financial resources. Pisa aimed to build a structure that would symbolize its glory and wealth, leading to the decision to construct Pisa Cathedral, the Leaning Tower of Pisa, and the Baptistery.

The Leaning Tower of Pisa was designed by architect Bonanno Pisano, but he passed away before its completion. The construction of the tower was carried out in three phases: the first phase from 1173 to 1178, the second from 1272 to 1278, and the third from 1360 to 1372.

During the first phase, the first three stories of the tower were completed, and it was during this time that the tower began to lean. This was due to the unsuitable nature of the ground in Pisa, composed of soft, wet sand and clay, making it inadequate for supporting a tall structure.

In the second phase, construction reached the seventh story. An attempt was made to correct the leaning angle by building the leaning side higher. However, this method further deviated the center of the tower, worsening the lean.

During the third phase, the top of the tower and the bell were installed, and again, the leaning side was built higher. As a result, the tower was completed with a 1.6-degree lean.

The name 'Pisa' is said to be derived from a Greek word meaning 'marsh'. When building the Leaning Tower of Pisa, the ground was only dug about 3 meters deep, which was too shallow to withstand the weight of the structure. Consequently, the south side of the tower subsided, causing it to lean.

Structure of the Leaning Tower of Pisa

The Leaning Tower of Pisa has eight stories, each with unique decorations and structures.

● The first story consists of 15 arches and serves as the entrance to the tower.

● The second story has 30 arches and is the heaviest story of the tower.

● From the third to the seventh stories, each has eight arches and features columns and decorations of different shapes.

● The eighth story is the bell tower, where seven bells are installed.

● There is a hole at the top of the tower for astronomical observations.

Despite being a leaning tower, the interior of the Leaning Tower of Pisa remains vertical. This is because the tower's staircase curves towards the leaning side.

The staircase has a total of 297 steps and allows visitors to ascend from the first to the seventh stories. The eighth story does not have a staircase, so a ladder must be used to access it. Inside the tower, there are informational plaques detailing the tower's history, structure, and preservation methods.

Causes of the Leaning Tower of Pisa and Preservation Methods

The Leaning Tower of Pisa began to lean during construction due to the uneven and soft ground that could not support the weight of the building. The ground in Pisa consists of wet sand and clay, causing the south side of the tower to subside more, leading to the lean. At that time, the tower increased its rotational angular momentum, causing it to lean even faster.

This phenomenon created a vicious cycle, causing the tower to lean progressively. While the Leaning Tower of Pisa became a world-famous landmark due to its tilt, it also faced the risk of collapse. The tower's lean increased to 5 degrees, and it was in danger of toppling over at any moment. To prevent this, several preservation efforts were undertaken.

In 1964, an 800-ton iron counterweight was installed at the top of the tower. In 1979, a clinometer was installed to measure the tower's lean. In 1990, construction was halted, and the tower was closed to the public. In 1993, 38 cables were attached to the north side of the tower to pull it upright. In 1995, a 600-ton counterweight made of lead and iron was installed on the south side of the tower. In 1999, 70 tons of soil were removed from the south side of the tower to reduce the lean.

These efforts reduced the lean to 3.97 degrees and increased the stability of the tower. In 2001, the tower reopened to the public, and in 2008, the preservation work was completed. Currently, the tower is expected to remain stable for another 300 years.

How to Visit the Leaning Tower of Pisa

The Leaning Tower of Pisa is a UNESCO World Heritage site and a popular tourist destination. Visitors are required to make reservations in advance to visit the Leaning Tower of Pisa.

The Leaning Tower of Pisa allows entry in groups of 50 people, with 15-minute intervals. The entrance fee for the Leaning Tower of Pisa is €20, and a combined ticket costs €27.

The Leaning Tower of Pisa is open from 9:00 AM to 6:00 PM, and it is closed on December 25th and January 1st.

The Leaning Tower of Pisa is a 10-minute bus or taxi ride from Pisa Airport and a 20-minute walk from Pisa Central Station.

When visiting the Leaning Tower of Pisa, consider the following tips:

• Wear comfortable shoes as the staircase is narrow and steep.
• Be cautious when climbing the staircase as it is inclined, especially if you are prone to motion sickness or have limited physical strength.
• Bring your camera to capture the panoramic views of Pisa from the top of the tower.
• Strike a pose near the tower for a famous photo opportunity, where you appear to be holding or pushing the tower.

Official website of the Leaning Tower of Pisa

www.opapisa.it

Fun Facts about the Leaning Tower of Pisa

● The Leaning Tower of Pisa was originally white, but over time, it has turned yellow. This is because the marble used in the tower's construction has oxidized due to its reaction with air and water.

● During World War II, the Leaning Tower of Pisa was used as an observation post by German troops. To avoid Allied bombing raids, a red cross was placed on top of the tower.

● It is said that Galileo Galilei conducted experiments on gravity at the Leaning Tower of Pisa in 1589. Galileo allegedly dropped objects of different weights from the top of the tower to demonstrate that they fall at the same speed, regardless of their weight. However, this is likely a story that originated from a book written by one of Galileo's students, rather than a factual event.

● In 2008, American magician David Blaine attempted a magic trick where he made the tower disappear. Blaine stood in front of the tower, unveiled a large cloth, and claimed the tower had vanished. However, this was merely an illusion created by concealing the buildings behind the tower and revealing a cloth shaped like the tower.

Conclusion

This concludes our blog post about the Leaning Tower of Pisa. The Leaning Tower of Pisa is a leaning tower and is often referred to as one of the wonders of the world. When you visit the Leaning Tower of Pisa, you can learn about its history, structure, and the secrets of its lean. The Leaning Tower of Pisa is a World Heritage site and requires ongoing preservation and management.