The reason why the Leaning Tower of Pisa is tilting.

The Leaning Tower of Pisa, the world's most famous leaning structure, is the result of carelessness and planning errors by its engineers.

The Leaning Tower of Pisa is the most famous leaning structure in the world. Photo: meros.

According to Ancient Origins, the Leaning Tower of Pisa was designed as a bell tower next to the Pisa Cathedral, in Piazza del Miracoli (Square of Miracles). This structure was part of a larger construction project in Piazza del Miracoli, Pisa, Italy. In addition to the bell tower and cathedral, engineers also planned to build a baptistery and a cemetery.

The Leaning Tower of Pisa was the third structure built as part of this project, but it was the last to be completed. Construction began in 1173. The architects in charge of the project were Bonanno Pisano and Gherardo di Gherardo. By 1178, three of the tower's eight floors were completed. However, it was only after the third floor was finished that the tower began to lean towards the north.

One reason for the tower's tilt is the geographical characteristics of the city of Pisa itself. The city's name dates back to 600 BC, from the Greek word meaning "muddy land." Therefore, the soft ground, primarily composed of mud, sand, and clay, is believed to be the culprit behind the Leaning Tower of Pisa's tilt.

Many other buildings in Pisa also lean due to being built on soft ground, including the 12th-century San Nicola church south of the Leaning Tower and the San Michele degli Scalzi church east of the tower.

Furthermore, the tower's foundation was made from a dense clay mixture and was about three meters deep. This foundation was not strong or deep enough to support the weight of the entire tower. These two factors combined led to the Leaning Tower of Pisa tilting.

The builders discovered the tower was leaning, but they could do nothing to stop it. They raised the pillars and arches on the leaning side to continue building the fourth floor. However, construction of the tower was halted for nearly a century due to Pisa's constant wars with other cities.

In 1272, construction continued under the direction of Giovanni di Simone. However, the war between Pisa and Genoa in 1284 halted the tower's construction. At that time, three additional levels were added. This shifted the tower's center of gravity, causing it to lean in the opposite direction. In 1319, construction began on the seventh level, housing the bell. This is also the highest level of the tower and was completed in 1372.

Initially, the Leaning Tower of Pisa's tilt was only 0.2 degrees. Over the centuries, this figure increased to 5.5 degrees in 1990. The difference in elevation between the top and bottom of the tower is 4.6 meters. Therefore, in the following years, a project was undertaken to stabilize the tower.

The ground beneath the tower was leveled, and anchoring devices were installed. The tower became more stable, but it continued to tilt. This wasn't the first time authorities had tried to prevent the tower from tilting. In 1934, dictator Mussolini had attempted the same, but the effort backfired and increased the tower's tilt.

In 2008, a second attempt straightened the tower by 48 cm. This was the first time the tower had stopped shifting in 800 years. Experts estimate that the Leaning Tower of Pisa will remain stable for at least another 200 years.

According to VnExpress