For centuries, the Leaning Tower of Pisa has been a beautiful accident—a 56-meter marble cylinder frozen mid-tumble, defying gravity and delighting tourists. By 1990, however, the joke nearly became a tragedy. The tower’s tilt had reached a terrifying 5.5 degrees, with the top overhanging the base by more than 4.5 meters . Experts gave it a grim prognosis: collapse “sometime between 2030 and 2040” .
What followed was one of the most dramatic and ingenious engineering rescue missions in modern history. Over the next decade, an international team of engineers, architects, and art historians worked to stabilize the tower without destroying its character. This is the story of how they saved it—and the surprising discoveries they made along the way.
The Patient: A History of Instability
To understand the rescue, you must first understand the patient. Construction on the campanile for the cathedral of Pisa began in August 1173, but within five years—as workers reached the third floor—the soft, marshy ground beneath began to give way . The tower’s shallow 3-meter foundation, resting on a unstable mix of sand and clay, was no match for its 14,500-ton weight .
Over the next two centuries, builders tried to compensate. When construction resumed in 1275, engineers built upper floors with one side slightly taller than the other, creating a subtle banana-like curve in the structure . It was a valiant attempt, but it only added weight and made the tower sink further. By its completion in 1370, the tilt was already pronounced .
Throughout the centuries, the tower’s lean fluctuated, gradually worsening as the clay compressed. In 1838, a misguided restoration actually made things worse—excavating a walkway around the base disturbed the groundwater and caused a sudden increase in the lean . Benito Mussolini, ever the authoritarian, tried to “fix” it by injecting cement into the foundation. Predictably, this also failed .
By 1990, the situation was critical. The tower was tilting at an accelerating rate of about 1 millimeter per year, and the pressure on the aging masonry was becoming unsustainable .
The Crisis: Closing the Tower
On January 7, 1990, Italian authorities made the difficult decision to close the Leaning Tower to the public for the first time in its history . For a monument that attracted over a million visitors annually, this was both a cultural and economic blow .
That same year, the Italian government convened a “Committee of 13 Experts” —a multidisciplinary team of geotechnical engineers, structural engineers, art historians, and restoration specialists . The committee was chaired by Professor Michele Jamiolkowski of Turin Polytechnic, a soft-spoken geotechnical engineer who would become the tower’s primary guardian . British engineering expert Professor John Burland of Imperial College London played a crucial role in developing the eventual solution .
Their mandate was clear: stop the tower from falling, but do not straighten it so much that it loses its identity. “The people of Pisa are delighted that the tower has been restored but not that it has been straightened,” the mayor later explained . The tilt was the monument’s soul; they had to save it, not erase it.
The First Steps: Temporary Measures
The immediate priority was stabilization. Engineers first wrapped the tower with steel cables and anchored them to large lead counterweights weighing approximately 600 tons, placed on the north side (opposite the lean) . These temporary “guy ropes” would hold the tower in place while a permanent solution was devised.
The anchors for these cables are still visible today—two bright white pulley anchors located behind the Palazzo dell’Opera, just outside the public restrooms . They remain the only visible remnants of the decade-long project, a subtle monument to modern engineering hidden in plain sight.
The Failed Experiment: The Frozen Nightmare
The first permanent solution proposed was ambitious: create a new underground foundation by freezing the soil and inserting 10 steel tension cables 45 meters deep . But when engineers began freezing the ground, the tower lurched dangerously. In one terrifying night, it tilted a full millimeter—equivalent to an entire year’s worth of movement . The experiment was immediately abandoned. “Panic is not the most correct word to describe that night,” John Burland later recalled. “Let’s just say we got out of it by a hair” .
The Brilliant Solution: Soil Extraction (Underexcavation)
The team regrouped and settled on a counterintuitive approach: instead of propping up the south side, they would remove soil from beneath the north side. The theory was simple: if the tower leans south because the south side is sinking, let the north side sink a little too. By carefully extracting small amounts of clay from under the north foundation, the tower would settle back toward vertical under its own weight .
This technique, known as “underexcavation” or sottoescavazione, was incredibly delicate. Engineers first tested it elsewhere in Piazza dei Miracoli to verify the soil behavior . Once confident, they began work in February 1999 .
Using a rotating screw auger system (essentially a giant corkscrew), they drilled 41 inclined holes beneath the north side of the foundation, removing about 38 cubic meters of soil in total . The process was agonizingly slow—approximately 100 kilograms of clay per day—allowing the tower to settle gently without sudden movement .
The Results: A Half-Degree of Salvation
By the time the underexcavation was complete in 2001, the tower had straightened by approximately 44 to 46 centimeters (about half a degree) . This returned it to the position it had occupied around 1700—visually unchanged to the casual observer, but structurally far more stable .
The total cost of the stabilization project was approximately €25–27 million (roughly $27 million USD at the time) . It was money well spent: engineers now confidently predict the tower will remain standing for at least 300 years .
The Reopening: December 15, 2001
On December 15, 2001, the Leaning Tower of Pisa reopened to the public . The event was celebrated with a handover ceremony on June 13, 2001, and a concert by Andrea Bocelli at the Presidential Estate of San Rossore .
But the reopening came with strict new rules. Visits are now limited to groups of about 30 people at a time, with tickets priced higher than before (25,000 lire, approximately €13) . The tower’s 293 steps are once again open to intrepid climbers, but the days of unlimited access are long gone.
The Restoration of the Stone (2001–2010)
With the structure stabilized, attention turned to the tower’s weathered skin. A second phase of restoration, led by Architect Gisella Capponi of the Istituto Centrale per il Restauro, focused on cleaning and conserving the 24,424 blocks of stone .
Years of exposure had taken a toll. Air pollution had created black crusts on the less-exposed sides, while wind and rain had eroded the more exposed surfaces . The restoration team, armed with lasers, chisels, and syringes, developed 11 different cleaning techniques to treat each type of stone individually .
“The stones were in an appalling state, mainly due to air pollution, though tourists and pigeons played a part,” explained Anton Sutter, the Swiss-born head restorer . The team worked through the night at times, cleaning each block by hand. The 7 million euro ($9.4 million) project was completed in 2010 .
The Afterlife: What’s Happened Since?
In the years since the restoration, the tower has continued to behave in fascinating ways. A 2013 study found that it had straightened an additional 2.5 centimeters since 2001, and by 2018, the total reduction in tilt reached about half a degree . Engineers now believe it will continue to straighten slightly before eventually—very slowly—beginning to lean again .
The tower is under constant surveillance. Sensors monitor everything: inclination, temperature, wind, even the opening and closing of cracks . Nunziante Squeglia, a geotechnical engineering professor at the University of Pisa, confirms that it is now “even more stable than hoped for in the 1990s” .
Visiting the Tower in 2026
Today, visitors can once again climb the tower and marvel at both the medieval craftsmanship and the modern engineering that saved it.
Current status: The tower is open year-round, but tickets must be booked in advance due to limited capacity. The best view, apart from the top, is from the north side of Piazza dei Miracles—and don’t forget to look for the two white pulley anchors behind the Palazzo dell’Opera, the only visible remnants of the 1990s rescue .
The Tower’s New Rivals
Interestingly, the restoration was so successful that the Leaning Tower of Pisa is no longer the world’s most lopsided building. That title now belongs to a medieval church tower in the German village of Suurhusen . The Capital Gate building in Abu Dhabi, with its intentional 18-degree slope, also leans far more dramatically .
But Pisa’s tower remains the beloved icon—and now, thanks to the brilliant work of Jamiolkowski, Burland, and their team, it will stay that way for centuries to come.
Conclusion: A Legacy of Ingenuity
The story of the Leaning Tower of Pisa’s restoration is not just about concrete and steel. It is about human ingenuity in the face of impossible odds. It is about respecting the past while securing the future. And it is about the delicate balance between preserving history and ensuring survival.
The next time you see a tourist pretending to “hold up” the tower, remember: they’re not just posing with a medieval marvel. They’re posing with one of the greatest engineering triumphs of the modern age.