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Leaning Tower of Pisa

✨ The fragile balance

The Leaning Tower of Pisa is the bell tower of Pisa Cathedral, in Tuscany, Italy. Its construction began in 1173 on the Piazza del Duomo, now a UNESCO World Heritage site. Built mainly from white and grey marble, the tower has eight levels and rises to about 56 metres on its higher side. Work did not proceed continuously: after the first three levels were completed, construction was interrupted for several decades, partly because of wars.

The tower was finally completed in 1372. Its circular form, arcades and columns are characteristic of the Romanesque architecture developed in Pisa during the Middle Ages. The famous tilt appeared while the tower was still being built. Its foundations are relatively shallow, and the ground beneath them consists of soft, water-rich sediments.

Under the heavy weight of the building, this ground compressed unevenly, causing one side to sink more than the other. The tower therefore began to lean toward the south. Over the centuries, the inclination increased and reached roughly 5.5 degrees before modern stabilization work. Engineers carried out extensive measurements and studies, then reduced the tilt by carefully removing small amounts of soil beneath the higher side.

The tower was closed to visitors from 1990 to 2001 while major safety work was carried out. Today, its inclination is about 4 degrees and is closely monitored. The tower remains both a medieval architectural monument and an important example of how soil, foundations and structural weight interact.

💡 Did you know?

Did you know that the Tower of Pisa began to lean when only 3 stories had been built? The ground was too sandy to bear its weight! Instead of stopping, the architects continued the work for 200 years, even trying to build the next floors slightly higher on one side to compensate, which gives the tower a slightly curved shape like a banana.

It is said that the great scientist Galileo used the Tower of Pisa for a famous scientific experiment. He supposedly dropped two balls of different weights from the top to show that they fell at the same speed! Thanks to the tower's tilt, the objects did not hit the walls during their fall, making it an ideal laboratory.

During World War II, the tower was almost destroyed! Soldiers believed that enemies were hiding there. But when a young officer saw the incredible beauty of this leaning monument, he decided not to order to fire. It is thanks to his passion for architecture that we can still admire it today.