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Still standing: The lean that refused to fall

The Leaning Tower of Pisa has tilted for centuries but never toppled. Unpack the story behind its famous lean, the science that explains it, and the engineering feats that saved it. From historical missteps to modern-day marvel, find out how this monument continues to defy gravity.

Progression of the tilt

Pisa Cathedral and Leaning Tower with tour group in foreground, Pisa, Italy.
Tourists lined up to enter the Leaning Tower of Pisa, Italy.
Leaning Tower of Pisa against a dramatic cloudy sky.
Reconstruction
Guide leading tourists at the Tower of Pisa Complex, Italy.
Leaning Tower of Pisa with Pisa Cathedral on the left during a walking tour.
Leaning Tower of Pisa and Pisa Cathedral in Italy with tourists exploring.
Leaning Tower of Pisa with tourists in Piazza dei Miracoli, Italy.
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Construction

Construction of the Tower of Pisa began in 1173. Originally intended to be a freestanding bell tower, the first stones were laid on the 9th of August, 1173.

Start of the tilt

The soil in Pisa is soft alluvial soil, which comprises loose sand, clay and shells. After just 3 stories were built, the foundations began to sink into the ground, and the tower began to lean on its south side.

Resting period

When the builders observed that the tower began to lean in 1178, construction was stopped. As a result of the city of Pisa going to war against Genoa, construction of the tower was halted for 94 years, until 1272.

Reconstruction

After almost a 100 years, work on the Tower of Pisa resumed under the engineer Giovanni de Simone. After another 12 years of reconstruction, the tower had 7 floors. But again, a war broke out between Pisa and Genoa, and the construction of the tower stopped once again.

Finishing the tower

In 1350, the construction of the 8th floor of the Leaning Tower of Pisa began under the architect Tommaso Pisano and took over 20 more years to complete. In 1399, the Tower was finally finished, and 7 brass bells were installed at the top.

The tilt worsens

In 1838, architect Alessandro della Gerardesca decided to expose the beautifully carved base of the tower in order to increase its value. In 1934, Benito Mussolini decided to make the tower perfectly vertical with the help of his men. Both of these severely worsened the tilt of the Tower of Pisa.

Danger of toppling over

In 1990, the tower was declared to be in danger of collapse. Computer algorithms predicted that a tilt beyond 5.44 degrees would result in the tower toppling over, but the tower was still standing at an alarming 5.5 degrees. Following the collapse of a different tower in another part of Italy, the Tower of Pisa was closed for repairs.

Restoration attempts

In 2001, after more than 10 years of restoration work, the Tower lost approximately 40 centimeters of lean. The tower was brought back to the lean it had 200 years in the late 1700s to about 4 degrees.

How engineers stabilized the tower

By the late 20th century, the Leaning Tower's tilt had reached 5.5 degrees—its top leaning 4.5 meters off center. To prevent collapse, engineers began a high-stakes stabilization effort.

Monitoring and emergency support

To begin, the tower was temporarily closed to the public in 1990 and encircled with steel cables anchored to underground concrete ring beams, acting like a seatbelt to prevent sudden movement. Engineers installed tilt sensors, laser alignment systems, and inclinometers to monitor every millimeter of motion in real time.

Counterweights

Engineers placed 600 tonnes of lead counterweights on the tower’s north side (the higher side) to slightly shift its center of gravity and slow down the tilt. This passive load helped stabilize the structure temporarily while permanent solutions were tested.

Soil extraction

The core stabilization method was underexcavation, a technique that involved removing small amounts of soil from beneath the north side of the foundation. As earth was gradually removed through angled boreholes, the ground compressed naturally, causing the heavier south side to settle and the tower to gently straighten.

Long term stability

By 2001, underexcavation had reduced the Leaning Tower’s tilt by 43.8 cm, restoring it to its early 19th-century angle of 3.97 degrees. The tower retained its iconic lean but shed the risk of collapse. Declared stable for at least 300 more years, it continues to be monitored—without any permanent addition of modern materials, preserving its historical authenticity.

The tower today: A triumph of preservation

Leaning Tower of Pisa upper levels with sunset sky in Pisa, Italy.

Today, the Leaning Tower of Pisa stands not only as an architectural marvel but as a testament to the success of modern preservation. Its lean—now stabilized at 3.97 degrees—is no longer a structural threat, but a defining feature that continues to captivate millions each year.

Visitors can climb its 273 spiral steps for sweeping views of the Piazza dei Miracoli and the Tuscan skyline, or simply admire the tower’s unmistakable tilt from below, one of the most photographed sights in all of Italy.

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Frequently asked questions about Leaning Tower of Pisa's fall

Has the tower ever fallen?

No, the Leaning Tower of Pisa has never fallen. Despite its dramatic tilt, careful engineering and stabilization efforts have kept it standing for over 850 years.

Will it ever fall down?

No, the tower is not in danger of collapsing for at least another 300 years since efforts have been made to stabilize the monument.

At what angle will the tower fall?

According to computer algorithms, it should have fallen when it tilted to an angle of 5.44 degrees, but it continued to stand even when it leaned at 5.5 degrees. Engineers quickly got to work to stabilize the tower before it collapsed.

How many years has the tower been slowly falling?

The Leaning Tower of Pisa began tilting just a few years after construction started in 1173, due to unstable ground beneath its foundation. That means it was slowly falling for over 800 years—until engineers halted the movement with stabilization work completed in 2001.

Who led the stabilization project of the tower?

A multinational team of engineers, led by Italian professor Michele Jamiolkowski, oversaw the efforts from 1990 to 2001. Their work is now considered a landmark in geotechnical engineering.

Is it safe to visit the tower?

Yes, it is safe to visit the tower as engineers have stated that it's under no immediate danger of collapse. Try booking your spot in advance as tickets are limited due to daily visitor cap.

What is the current angle of the tilt of the tower?

The current angle of tilt of the Leaning Tower of Pisa is about 4 degrees (3.97 to be accurate).

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