The Tower of Pisa – Architectural Jenga (1173 -1319)

You’ve heard and I’ve heard, usually right after making some grave error. Someone tells you even mistakes can lead to great success. And if we are being honest, I think we like that sentiment so much because our day to day life is riddled with mistakes. It’s natural. It’s human.

But no one likes it when architects make mistakes, especially when it leads to dangerous situations or possible collapse. In fact, most architects in this scenario would be sued. Your building is leaning almost 13 ft out of plane? Lawsuit waiting to happen. Luckily, the architect of the Tower of Pisa died before the crazy litigious society of today cropped up, and before the tower itself was even close to being completed.

The Tower of Pisa does not lean by design. In fact, it’s very standing is a result of a whole slew of mistakes along its history. Sometimes making mistakes means missing your stop (and not realizing until 4 stops later), and sometimes it means building a 14,500 ton leaning tower.

The precariousness is captivating…

But I think if you asked around, a lot of people would describe the Leaning Tower as a success instead of a failure. So maybe after all, we proved that old adage right.

The tower of Pisa was first built on the Piazza del Duomo to give prominence to the area. It was meant to draw visitors to a complex that already had a cathedral and a baptistry (and beautiful ones at that). But mostly, it was built for reasons common to almost all architecture. It was meant to show off. It reflected affluence and intelligence. And most of all beauty.

This is the rest of the complex, which the tower offers a great view of!

Pisa was once a town of sailors and a very important commercial center in the Mediterranean. Filled with wealth and prestige wrested from far-off lands with their invention of the naval ram, it was experiencing a golden age. After freeing the Balearic islands from the Moors with the aid of the Pope, the Pisans had a lot of booty to spend. And so, they improved all their buildings. That tower stood as a testament to all the rest of Italy that Pisa was better off. It was essentially the built form of this emoticon: 😛

And so construction began. Intricate carvings, columns, and arches make up the entirety of the tower’s design. For medieval Europe, this design was forward thinking. Nowadays, it seems timeless.

Arches on arches. I don’t think it was an accident that arches are one of the best shapes for dispersing weight.

The bottom floor is made up of 15 arches, which double on the upper floors, containing 30 arches each. These arches are key for structural support. They help disperse the load of the upper floors evenly. Unfortunately, they are dispersing a lot of load onto unequal soil. Luckily, the tower was built with limestone and lime mortar, and only covered with marble. That flexible limestone is one of many reasons why it is still standing today. The flexibility in the stone stopped cracks and withstood all the extra pressures from the lean.

Nowadays, we know that clay is one of the worst soils for construction. It has a vast amount of water in it. It expands and contracts with frost and temperature variations. Whether or not they knew that back then is anyone’s guess. I would lean towards no (get it – lean, haha) since they decided to build a rather high and heavy tower on top of it, but maybe they were just making the most of the land they had. If I was building a tower on undesirable land in the present day, I could rely on many different methods to ensure stability. Deep foundations, replacement of soil, bigger footings, flooding the soils, and piles are all modern methods employed in a  scenario like this. But in 1173, they were not.

Instead, they built a 9 ft deep foundation (which is really rather small) and by the third floor it began to tilt.

I can hardly imagine the atmosphere in 1178, watching this very heavy, stone structure start to lean. But if I had to, I guess it would be something like jenga. You know that moment as you watch someone pull a block and the whole thing wobbles a little and there is just a general inhale of breath. I’m pretty confident that that’s how the residents of Pisa felt. You see at this point, three stories committed, the 9 foot foundation could not really be added to. The depth didn’t account for the fact that half the site stood on soil that is pretty much the worst for all architecture (let alone a heavy, stone tower).

So what happens after that collective breath in? They just leave it for a 100 years. The Pisans had more to worry about than a tilting tower. They stood in a very long battle against the rival Genoans. Ironically, this distraction of decades long war probably led to the tower’s survival. Over time, the soil compacted slightly and was able to hold the structure, even if the lean gradually worsened.

Pretty sure the citizens of Pisa weren’t as strong as me, and therefore couldn’t hold the whole thing up 😉

Because in Jenga you just got to keep going, Giovanni di Simona starts adding to the perilous structure in 1272. Four more floors were installed. Simona thought he was being smart when he decided to make one side of each floor taller than the other, in order to compensate for the original lean. You have to give it to him for the attempt and for wanting it to look symmetrical, but unfortunately the tower just leaned more and as weights and loads shifted, the weird heights on each side further increased the problem.

This construction period also did not last very long. Within 12 years, it was once again at a standstill. The Genoans popped up again and unfortunately for the Pisans, their fleet began its eventual decline. It’s said that their loss can be attributed to Pisa’s own Count Ugolino della Gherardesca. Rather tragically, he and his family were thrown into a prison tower (not this one, but another) and left to die of starvation. Good old Dante would later call this figure the cannibal count, starting a rumor that he was reduced to eating his own children in the tower. I felt like I just had to add this aside because it is not often that a cannibal count is linked to anything, let alone architecture.

It wasn’t until 1319 that the 7th floor was completed and the tower was done. However, this beacon of grandeur and prosperity only stood as such for a little while. In 1392, Florence bought all of debt-riddled Pisa, sending most of the Pisans into servitude. In between those two events, a bell tower was added to the top, because hey, it was already leaning so why not add more?

The bells are back!

At this point, you have to figure that bad luck had had enough of the tower of Pisa, or at least that there had been enough mistakes. But you, my friend, would also be mistaken.

In 1838, Alessandro della Gherardesca digs a pathway near the base of the tower to laud it’s craftsmanship. And this little act is probably the pinnacle ‘architects doing dumb things’ scenario. I think almost anyone could tell you that digging out the soil that was just barely supporting a tower that had been leaning for a good 600 years is a bad idea. And they would be right. The tower leans more!

In 1934, Mussolini would try his hand at stabilizing it. Believing that it’s lean said more about the failure of Italy than its charm, he decided to drill 361 holes in the foundation and have them filled with cement. Instead of acting as he imagined and counterweighting the structure, it sank even further into the clay.

Maybe the only lucky thing about the tower at this point was it’s very narrow escape from being bombed during WWII. Fortunately, despite German troops location in the tower, the Allies prevented it’s bombing one night because of the beauty of the site. Luckily, the Germans would quickly retreat and the Allies weren’t forced to change their position.

Still standing, but more importantly, still leaning.

By 1964, the tower stood in a pretty perilous state, leaning at 5.5 degrees. The Italians had to take some serious steps to protect the landmark and right the lean. Although, it was imperative to preserve the lean too. Everyone was pretty confident that a regular tower was not going to muster the same amounts of tourism as a leaning one. With a team of architects and engineers on the case, it was decided to add a 800 ton counterweight to balance the structure. In 1990, the bells were removed and over the next 11 years, it was straightened about 45 cm through a process of soil removal, draining, and adjustments to the water table of the immediate area.

Now just because it was straightened, please do not think this tower is anywhere near straight. It still tilts at 3.97 degrees, meaning that the top of the tower is 12’ – 10” out of plumb with the bottom. Except, now it is reasonably safe for you to climb it. 297 steps up, you can be transported into a view of yesteryear.

If there were no cars, I could believe I was in a different century perhaps.

It is not frequent that we look past the lean and think about the actual structure in its own right. In 1173, the height designed for this tower was without precedent in Europe. It’s ability to reach such great heights is made possible by the arch design I discussed before. And so, it was also the world’s largest leaning tower until 2010. Even though it presently stands six feet shorter than it once did.

Although most architecture does not lean to this extent, all architecture comes with its own missed opportunities and mistakes. These derive from the fact that it is designed by people and no person is flawless. But part of the appeal of the tower of Pisa is not everything it did right, but instead it’s one major weakness. I think we can all take a note from this building, and make the most of ours.

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