The Leaning Tower of Pisa: the Mount Everest of Lopsided Buildings
Updated: May 24
Considering a trek to see the famous Leaning Tower of Pisa? And wondering why the Leaning Tower leans? This monument is one of Italy's most photographed landmarks due to its perilous slant. It's almost akin to visiting the Eiffel Tower in Paris.
The off kilter Leaning Tower became popular purely because of bumbling mistakes. The original architects chose a terrible location with soft soil. When the mistake was apparent, they doubled down. 700 years of effort and interventions have failed to straighten the Leaning Tower.
But Italians know how to turn a disaster into a money making tourist attraction. Today, gag photos of people "holding it up"and trinket shops abound. If you want to learn about the sordid history of the famous but fragile Leaning Tower and the reasons for its famous tilt, read on.
What is the Leaning Tower of Pisa?
The Leaning Tower is part of Pisa's UNESCO-listed Field of Miracles complex, an important assemblage of Romanesque, Medieval, and Early Renaissance art and architecture.
Contrary to most people's expectations, the Leaning Tower is the least impressive site. You may not even realize before you get to Pisa that the Leaning Tower is merely the cathedral's bell tower.
It's located in a posterior position behind the cathedral. The bell tower has stacked concentric colonnades and looks rather like a massive wedding cake. Its famous tilt makes it a sort of architectural folly.
Here are some facts about the Leaning Tower, whose construction began in 1173.
✔ The original architect was most likely Bonanno Pisano.
✔ It's almost 200 feet tall, 55 feet wide, and weighs 14,000 tons.
✔ There are 8 stories and 6 stories of columns.
✔ You'll have to hoof it up 294 steps to take in the view from the belfry.
✔ 135 of the 180 marble columns have been replaced.
✔ It's currently leaning 15 feet off its vertical axis.
✔ There are 7 bells at the top that weight over 23,000 pounds.
✔ It's not the only leaning bell tower in Pisa. The tower of San Nicola Church also leans.
✔ Galileo learned principles of gravity by dropping lead balls from the belfry.
The Leaning Tower is nothing special. The magnificent Giotto bell tower in Florence is twice as tall, 56 vs. 92 feet. Perhaps if the builders of the Giotto bell tower had known how much revenue a town could generate from an oddity like a leaning tower, Florence would have built its crooked as well.
An Architectural Disaster: Why Does the Leaning Tower Lean?
Some art historians refer to Pisa's Leaning Tower as the "greatest architectural disaster since Babylon." But, curiously, that disaster has just drawn throngs of tourists to Pisa. Some Pisans don't care, noting that the tower shows more stability than the Italian government. In fairness, the Leaning Tower has survived four earthquakes and two world wars.
So why does the Leaning Tower lean? Simply put, Pisans chose the wrong construction site. The Leaning Tower has an unstable base.
If you look around you in Pisa, you'll realize that everything is crooked. The Duomo is crooked, the Baptistery is leaning. They're all crooked for the same reason -- they were built on mushy alluvial Pisan soil. Because the bell tower loads weight on a particular point in the mush, it leans the most of all the monuments.
The foundation stone for the leaning tower was laid in 1173. The world's best known faulty tower starting slanting south immediately thereafter. Since then, architectural experts have come closer to destroying it than saving it.
When they started building, the medieval architects made two mistakes. First, the tower was erroneously built on a shallow and insufficient foundation, a base of three meters of dry masonry. It wasn't deep enough to support the tremendous weight of the tower. The second mistake they made was to load too much weight onto too little surface area.
As they were building, the tower started leaning south. The soil on the south side was even more spongy and compressible. Construction halted after just 10 years. At only the height of the third ring, the structure had already sunk 40 centimeters into the ground.
Misguided Interventions To Fix the leaning Tower Tilt
At his point, you'd think the Pisan authorities might has re-assessed going ahead with the project. Instead, they just plowed blindly ahead. A century later, construction recommenced and they add three more arcaded stories to the tower.
What they thought would fix the problem was to curve one side of the structure like a banana. So the structure would lean, but the curve would correct the optics.
But, without a proper foundation, the entire structure sunk further into the ground, leaning by a full meter. The Pisans interrupted building again. In 1350, they decided to add the belfry onto the bell tower and call it a day. So the structure was shorter than originally planned, but complete. But the tower continued to lean.
700 years of leaning resulted in a drastic lean -- the sort a lean that inevitably leads to a catastrophic collapse. In 1990, the tower was closed to visitors for a decade because of its instability. Something needed to be done to save Pisa's star attraction.
The Italian government enlisted top engineers to fix the problem. They decided to correct the lean by adding 600 tons of lead weight to the side against the lean. They hoped that the counterweight would correct the lean. But this only caused the tower to sink further.
This is 1992, not the dark ages. You'd think architects could have found a viable solution. The Pisans promptly abandoned this latest idea. The Leaning Tower seemed doomed to droop.
But, desperate, they decided to try something else. Architects affixed gigantic steel cable girdles around the central cylinder of the tower. This served the dual purpose of protecting the masonry and thwarting the pull of gravity. The girdles were then attached to a nearby building, giving the monument a pair of skinny steel suspenders to help it stand straighter.
If the tower had gone down, it likely would have pulled the roof off the adjacent building. Plus, this fix was also ineffective. And it was visually unappealing. Today, the only remaining remnant of this failed experiment is two large white anchors on the Palazzo dell'Opera.
A Relatively Successful Intervention: Soil Extraction
In the early 2000s, a solution was found. It was the most important intervention and conservation effort to date. Engineers drilled holes underneath the north side of the tower. They gradually removed the dirt under the tower, creating a space or vacuum. The tower gradually began to fall back on itself. It recovered a full 50 centimeters.
At that point, they injected the base with concrete, freezing the tower in place. The lean was temporarily halted. But it's predicted to start leaning again in the early 23rd century, when another intervention will be needed.
The tower gets regular check ups. It's one of the most monitored buildings in the world. 100 sensors give hourly readings on temperature levels, wind velocity, soil movement, and micro fissures.
Oddly, at this juncture, the complete righting of the tower would be as big a disaster as its collapse. Pisa is synonymous with its Leaning Tower. And the lean is part of its charm.
Climbing the Tower: the New Threat
Having stabilized the Leaning Tower, Pisa decided to celebrate by ... taking another ill-advised step. They decided to market the tower by selling tickets to climb it. And the tickets are wickedly expensive at €18.
Thousands of people a day climb the Leaning Tower. This many people climbing daily poses a threat of long term damage to the tower, accelerating its decay. It's a rather dumbfounding move despite the revenue, a short sided approach to preserving the monument.
But most people seem to think it's a fun, disorienting, and vertigo inspiring experience. Be forewarned, the steps are uneven and slippery. Don't crack your head on the marble of the low doorways. To be sure, there's great panoramic views from the top.
Bottom Line: the Leaning Tower is a Tourist Trap
The Leaning Tower doesn't deserve its widespread fame. It's just a botched oddity that tends to make Pisa a one site "hit and run" town. You might even look at the Leaning Tower, and then head out for an apertivo, it's so underwhelming. Having said that, I think the town of Pisa is completely worth visiting. Just not for the Leaning Tower.
What Else Is There To Do in Pisa Besides the Leaning Tower?
Fortunately, if you visit Pisa, there are so many other amazing sites and landmarks to see. The Field of Miracles is chock full of medieval and early Renaissance art. The exuberant Duomo, or Pisa Cathedral, is fascinating. The Baptistery appears to be dripping in lace, it's so ornate. Inside is one of the most important pulpits of the early Renaissance.
Not only that, you can visit the Monumental Cemetery, which was once called the "Sistine Chapel of Pisa." It has a rather gory fresco called The Triumph of Death, which is world renowned. Plus, there are two other museums -- the Duomo Museum and the Museum of the Sinopie. The former houses one of the world's most famous busts of Julius Caesar.
So Pisa is definitely worth a stop or day trip in Tuscany. It's an especially easy day trip from Florence.
Click here for my complete guide to all of Pisa's must see sites. If you want to know how to climb the Leaning Tower or get visitor information for the other Field of Miracles sites, click here for my guide with tips and everything you need to know before visiting Pisa.
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