Collapsing soon? The Leaning Tower of Pisa has been falling for 800 years, so why hasn’t it collapsed into rubble yet?

The Leaning Tower of Pisa looks like the kind of mistake that should have corrected itself by collapsing centuries ago.

That is the basic mystery the host lays out in the video from Engineering The Impossible. In the video’s telling, this famous bell tower should already be a pile of shattered white stone on the pavement below. It has spent most of its life leaning, sinking, and slowly edging closer to failure, all because it was planted on soft, uneven ground with a foundation that was never deep enough for a structure of its size.

And yet it is still there.

That is what makes the tower so fascinating. It is not just a famous tourist photo backdrop. It is a long-running engineering emergency that somehow turned into one of the world’s most successful landmarks.

The Problem Started The Moment They Built It

The host says the real trouble began in 1173, when workers started laying the foundation for what was supposed to be a grand white-marble bell tower for Pisa’s cathedral complex.

On paper, it was an impressive project. The plan was for an almost 185-foot tower with multiple levels of arches and columns, rising over the city as a show of wealth and civic pride. Pisa at the time was a powerful maritime republic, and this was meant to look like it.

But according to the video, the part that mattered most was the part no one would admire in a painting: the ground underneath it.

The host says the builders dug only about 10 feet down for a tower that would eventually weigh tens of millions of pounds. Worse than that, they placed it on old river deposits made of sand, clay, and silt, the kind of patchy, compressible soil that does not like carrying huge loads evenly.

That combination was a recipe for trouble.

The video compares it to shoving a beach umbrella only a few inches into the sand and then acting surprised when it starts to tilt. It is a funny comparison, but it gets the point across fast.

The Tower Started Leaning Almost Immediately

The tower did not wait centuries to announce there was a problem.

The host says that by around 1178, when the first few levels had gone up, it had already started to lean. Not dramatically at first, but enough that people working on it likely noticed something was off.

That left the builders with an ugly choice. Tear it down and start over, or hope the ground would settle and the lean would stop.

Officially, the video says, construction paused because of wars and financial problems. But that long interruption turned out to be one of the reasons the tower survived. For nearly a century, the stone structure sat there pressing into the ground, while the soft soil below slowly compacted and adjusted.

Ironically, that delay may have saved the whole building.

If they had rushed to finish the tower in one continuous push, the host argues the unstable ground might have given way much faster and sent it over.

Medieval Builders Tried To Cheat Physics

When construction resumed in 1272, the lean was obvious.

So, according to the video, the masons did something both clever and slightly desperate: they built the upper levels a little taller on one side in an effort to compensate for the tilt. That is why the tower is not just leaning, but also subtly curved.

The host describes it as a kind of medieval Photoshop.

It did not solve the root problem, but it did help explain why the tower has that slightly bent look if you study it carefully. The structure was trying to correct itself even as the foundation kept working against it.

The host says the tower and the soil eventually found a rough, uneasy balance. The ground was weak, but that weakness also helped by deforming gradually instead of cracking and failing all at once. Over time, the tower sank by about 10 feet and leaned farther south, while the soil kept redistributing the stress.

That bought time, but not safety forever.

For Centuries, It Kept Leaning And Nobody Could Truly Stop It

By the 1800s, the host says more accurate measurements showed the tilt was approaching 5 degrees.

Even then, the tower remained standing. It shifted with the seasons, reacted to rain, and moved with changes in the water table. It even survived earthquakes that might have wrecked other structures.

That is one of the strangest things about Pisa. The same weak ground that made it lean also helped absorb shocks in ways that may have kept it from breaking apart.

Still, by the late 20th century, the situation was becoming too dangerous to romanticize.

The host says that by the 1980s, the tower was no longer just an architectural oddity. It was a major public hazard and an economic crisis in waiting. Pisa depended heavily on the tower’s fame. Hotels, cafés, souvenir shops, guides, and ticket sales all fed off that crooked silhouette. In the video’s words, the city was living off its “golden goose and marble.”

By then, that goose was in trouble.

The 1990s Rescue Effort Was Desperate And Weird

The crisis sharpened after another Italian masonry tower, the Civic Tower of Pavia, collapsed in 1989 and killed four people.

The host says that less than a year later, in January 1990, the Italian government closed the Leaning Tower to visitors. The bells were removed to reduce weight. Cables were attached for emergency stabilization. Families living in the potential fall zone were told to move.

And the numbers were bad.

According to the video, by 1990 the tilt had reached about 5.5 degrees. Some independent analyses suggested the critical collapse angle was around 5.44 degrees. On paper, the tower was already past it.

That is the kind of detail that makes the whole story feel less charming and more alarming.

An international team of engineers and geotechnical experts was brought in, including British soil mechanics specialist John Burland. Their job was brutally simple: save the tower without demolishing it, straightening it too much, or changing the way it looked.

That is a nearly impossible set of instructions. Make it safe, but do not ruin the thing people came to see.

The Solution Sounded Wrong Because It Kind Of Was

The host says the first emergency step looked ridiculous but worked.

Engineers built a concrete ring around the base on the higher side of the tower and stacked hundreds of tons of lead ingots on it, like giant gym weights, to counter the lean. It was ugly, awkward, and terrible for postcard views, but for the first time the tower moved slightly back toward vertical.

That bought time.

Then came a series of bigger ideas, some of which failed. At one point, the video says, engineers cut into a circular walkway at the base while working on an anchoring system. They had assumed it was separate from the foundation. It was not. The tower suddenly shifted more in one night than it normally would in a whole year.

That must have been a terrifying moment.

The anchor idea was abandoned, and the team went back to the drawing board.

Then came the solution that sounded the most backwards of all: instead of supporting the sinking side more, they would remove soil from under the raised side.

Taking Soil Away Saved The Tower

The video says the successful method was called underexcavation.

Before trying it on the real structure, the engineers tested the idea in the same piazza, using a loaded pad and carefully removing soil beneath it. The test behaved exactly as predicted. That gave the team enough confidence to proceed.

They drilled small angled holes beneath the north side, the higher side, and removed tiny amounts of soil every few days. Then they stopped, measured everything, checked for cracking, and only continued if the movement stayed controlled.

Over the late 1990s, the host says they removed roughly 70 metric tons of soil.

It does not sound like much compared to the size of the tower, but it was enough. Little by little, the structure rotated back toward vertical. By 2001, the top had shifted back by about 17 to 18 inches, and the tilt had dropped to just under 4 degrees.

That was enough to reopen it to the public.

Why It Has Not Collapsed Yet

So why has the Leaning Tower of Pisa not turned into rubble after all these centuries?

The video’s answer is that it survived through a bizarre mix of bad design, lucky delays, forgiving soil behavior, and extremely careful modern engineering. The same weak ground that caused the lean also slowed the failure. The long construction pause let the soil settle. The medieval builders bent the upper levels to compensate. And when the tower finally got close to disaster, modern engineers stabilized it with a solution that sounds wrong until you understand the mechanics.

The tower still leans. It still is not “fixed” in the normal sense.

But according to the host, it now sits in a safer sweet spot, still unmistakably crooked, but no longer creeping toward collapse the way it was in 1990. Its tilt is now around 3.97 degrees, down from the frightening 5.5-degree range before the stabilization work.

That is probably the most remarkable part of the whole story. Pisa did not save the tower by making it normal. It saved it by making it just stable enough to stay famous.