Fame from Fault: Reasons Why the Famous Tower of Pisa Leans
The Tower of Pisa, also known as the Leaning Tower of Pisa, is one of the most iconic buildings in Italy. As its names suggests, this tower is best known for its tilt, and is perhaps the most renowned leaning building in the world. This tilt, however, was unintentional, and was the result of poor planning on the part of its architects. The city’s physical geography is also partially to be blamed for the tower’s tilt, as several other buildings in Pisa are tilted as well.
The Tower’s History
The Tower of Pisa was originally built as a campanile, or bell tower, next to the Cathedral of Pisa, in the Piazza del Miracoli (meaning ‘Square of Miracles’). The building of these two structures was part of a project to enrich the Piazza del Miracoli. In addition to the bell tower and the cathedral, the construction work also involved the building of the Baptistry and the Monumental Cemetery.
The Tower of Pisa was the third of these structures to be built (the fourth being the Monumental Cemetery), though it was the last to be finished. The construction of the bell tower began in 1173, and the architect responsible for this building phase was either Bonanno Pisano or Gherardo di Gherardo. By 1178, three of the tower’s eight stories had already been built. It was just after the completion of this third story that the tower began to lean north.
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Leaning Tower of Pisa ( Public Domain )
Physical Geography and Poor Foundation
One factor that contributed to the tower’s tilting is the physical geography of Pisa itself. This city got its name in 600 BC from a Greek word meaning ‘marshy land’. Thus, the city’s soft soil, which consists of mud, sand, and clay, is partially to be blamed for the tower’s tilting.
Incidentally, there are a number of other buildings in Pisa that are leaning as a result of being built on the soft soil. These include San Nicola, a 12th century church to the south of the Leaning Tower, and San Michele degli Scalzi, an 11th century church to the tower’s east.
Additionally, the tower’s foundation, a dense clay mixture 3 meters (9.8 feet) deep, was neither strong enough nor deep enough to support the tower’s weight. Thus, the building’s weak foundation and the city’s soft soil are responsible for the Tower of Pisa’s tilt.
Pisa Cathedral & Leaning Tower of Pisa ( Public Domain )
Although the builders noticed the tilt, it was likely that there was not much they could actually do to stop the tower from tilting. It is said that they tried to compensate by making the columns and arches of the third story on the sinking northern side slightly taller, and then proceeded with the fourth story. At this time, however, work on the tower was suspended for almost a century, as Pisa was engaged almost continually in military conflicts with other Italian city states.
Attempts to Rectify the Tower of Pisa’s Position
In 1272, work resumed, this time under the direction of Giovanni di Simone. Work halted again in 1284, however, as a result of Pisa’s war with Genoa. Nevertheless, the addition of another three floors to the Tower of Pisa caused a shift in its center of gravity, which resulted in a reversal in the direction of its tilt from the north to the south. It was only in 1319 that the 7th story was added, whilst the bell-chamber, which was also the last story, was completed in 1372.
Putti Fountain, Pisa Cathedral, and the Tower of Pisa ( Public Domain )
It has been said that the initial tilt of the Tower of Pisa was only 0.2 degrees. Over the centuries, however, this figure increased, reaching 5.5 degrees by 1990, with the top 4.6 m (15.1 ft.) of the tower to the south of its bottom. Thus, in the following decade, a project was carried out to stabilize the Tower of Pisa.
The soil beneath the tower was levelled, and anchoring mechanisms were introduced. Although the tower had become more secure, the leaning continued. It may be mentioned that this was not the first time that an attempt to rectify the tower’s position was made. In 1934, for instance, Mussolini tried to fix the Tower of Pisa, though he only managed to make the tilt more severe.
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In 2008, it was reported that a second attempt to stabilize the Tower of Pisa had managed to make the iconic building 48 cm (18.9 inches) straighter. This was the first time in the tower’s 800-year history that it stopped moving. Experts estimate that the tower will remain stable for at least another 200 years.
Featured image: The Leaning Tower of Pisa at night. Photo source: CC BY NC 2.0
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