How did Brunelleschi build the dome?

Gasp! Imagine a massive church with a giant, gaping hole in the roof for over 100 YEARS! That’s what happened in Florence, Italy, way back in 1420! Nobody knew how to cover it up—it was impossible! Enter Filippo Brunelleschi, a goldsmith who probably wasn't supposed to be an architect, but he had a SECRET plan to win the building contest! How did he do it?! He invented brand new giant cranes that looked like giant wooden dinosaurs and figured out how to stack FOUR MILLION bricks in a crazy, cool herringbone pattern without any wooden supports! It’s still the BIGGEST brick dome ever built 600 years later! Join Mira and Finn as they uncover the secrets of this impossible building project. Get ready for history that is definitely NOT boring!

Transcript

SPEAKER_01 0:00

Welcome to History's Not Boring by Kidopoly.com. I'm Mira! And I'm Finn! And today we have a super special shout-out for Charlotte, age five, listening all the way from Chicago. Charlotte, you said the story of Brunelleschi's dome is so cool, and you are absolutely right!

SPEAKER_00 0:22

She knows the best stories, Mira. I love hearing about cool people like that.

SPEAKER_01 0:27

We do, because today we're tackling a problem so huge it stomped everyone for over a hundred years.

SPEAKER_00 0:35

A hundred years? What was the problem? Was it a scary monster?

SPEAKER_01 0:40

Worse, Finn. It was a giant gaping hole in the roof of the main cathedral in Florence, Italy. We're talking about the Santa Maria del Fiore Cathedral, and this hole was a gigantic, embarrassing gap right over the city.

SPEAKER_00 0:56

A giant hole? That sounds like it would let in all the rain. And the cold. It did! Imagine this.

SPEAKER_01 1:04

It's the year 1420. The city of Florence is amazing, full of rich people and beautiful art, but their biggest church has this massive hole right in the centre, and no one knows how to build a dome to cover it. It's been open to the sky since they stopped working on it way back in 1300.

SPEAKER_00 1:23

Whoa, a hundred years of rain on the inside. That's like leaving your biggest toy outside in a thunderstorm for a century.

SPEAKER_01 1:31

Exactly. But today we find out how one genius named Filippo Brunelleschi figured out how to build the largest brick dome the world had ever seen without any wooden supports underneath. It's truly impossible architecture.

SPEAKER_00 1:46

Okay, so Florence, Italy, way back in 1420. What was it like there? Were there knights everywhere?

SPEAKER_01 1:53

Not exactly knights, but it was the start of the Renaissance, a time when people got super smart about art and building. Florence had about 75,000 people, and they were super proud. They wanted the biggest, most beautiful cathedral dome in all of Christendom to show everyone how powerful they were.

SPEAKER_00 2:14

So the hole was like a giant, embarrassing sign that said, We give up.

SPEAKER_01 2:19

Yes, the empty space, called the Oculus, was almost 145 feet across.

SPEAKER_00 2:26

That's wider than two school buses parked end to end. That is so wide. But if they wanted to build a dome, they needed a giant wooden support, right? Like a giant mould for the ceiling to rest on while it dried. That's the problem. They couldn't build one.

SPEAKER_01 2:43

The space was too wide, almost 145 feet up in the air. They didn't have enough wood in the entire region of Tuscany to build the temporary wooden frame, called centering, that big.

SPEAKER_00 2:57

No wood. So they were just stuck. Did they try to just use really, really long sticks? They were stuck.

SPEAKER_01 3:05

So in 1418, they held a big competition to find a solution. The prize money was 200 gold florins. That was a huge amount. Many smart people tried, but they all came up with ideas that needed that giant wooden frame, which everyone knew was impossible.

SPEAKER_00 3:24

Who was the genius who finally solved it? Was he a super strong builder?

SPEAKER_01 3:29

His name was Filippo Brunelleschi, and he was actually a goldsmith and a clockmaker. He wasn't even a famous architect. He travelled to Rome and studied the ancient Pantheon, which has a dome, but it's much smaller.

SPEAKER_00 3:44

A clockmaker. So he had to figure out how to build it and how to get all the materials up so high. That's like needing to climb Mount Everest to put a tiny roof on your house.

SPEAKER_01 3:56

He proposed a secret plan. He wouldn't build a wooden frame underneath at all. He'd build the dome using a special brick pattern that would support itself as it went up. He won the competition in 1420, but everyone was so nervous about his secret plan, they only let him build the first few feet.

SPEAKER_00 4:15

He had to prove it first. That's so unfair. What if his secret plan didn't work and everything crashed down on Florence? That was the fear.

SPEAKER_01 4:25

But Brunelleschi was clever. He knew he also needed a way to lift the heavy materials, like the four million bricks, way up to 150 feet. So he invented new machines.

SPEAKER_00 4:39

New machines? Like what kind of machines? Did they have giant pulleys? Better!

SPEAKER_01 4:45

He designed a special reversible hoist, a new kind of crane. It used oxen walking on a huge treadmill inside a wooden drum to lift the stone and bricks. And here's the coolest part. If the oxen got tired, he could make them walk backward to lower the load without having to switch out the animals.

SPEAKER_00 5:06

Wait, like a giant hamster wheel, but for an ox, imagine being an ox walking in circles all day to lift bricks that high.

SPEAKER_01 5:15

It was genius! These new cranes let them lift huge stones up to 160 feet high. The dome itself was massive. It was about 145 feet in diameter, and the peak rose over 300 feet above the ground. That's taller than a 30-story apartment building.

SPEAKER_00 5:36

So he built the machine and then they started on the wall. How did he make the bricks stay up without the wooden mould?

SPEAKER_01 5:43

He used a brilliant pattern called a herringbone. Imagine laying bricks so that each brick is supported by the ones on either side of it, leaning against each other like little dominoes that lock together. He only laid a few courses of bricks at a time, letting them set before building higher.

SPEAKER_00 6:03

So the bricks were supporting themselves while they were being built? That sounds super tricky. Did he have to yell at the bricklayers a lot? He had to be super strict.

SPEAKER_01 6:14

To make sure the two shells of the dome, an inner and an outer one, didn't pull apart, he used sandstone chains embedded in the brickwork every few feet. These chains acted like giant invisible rings holding everything tight. The work went on for years, from 1420 all the way to 1436.

SPEAKER_00 6:37

Fifteen years of building. That's longer than I've been alive. Did anyone try to sabotage it? Maybe a rival architect got jealous. Oh, absolutely.

SPEAKER_01 6:47

Building it was a battle. When they started, the workers had to climb up and down scaffolds that were miles high, basically. Many people thought the dome would collapse when it reached a certain height, or when they reached the which is the base it sits on.

SPEAKER_00 7:02

What did he say to them when they got scared? Did he have a big inspiring speech?

SPEAKER_01 7:07

He actually did something funny to stop people from stealing his design ideas. If a worker showed up and asked, Filippo, what do I do next? He would tell the first guy to do one thing and the second guy to do the exact opposite. He kept them totally confused.

SPEAKER_00 7:24

That's sneaky, but I guess it kept his secret plan safe. So how did they finally seal that giant hole at the very top?

SPEAKER_01 7:32

That was the final hurdle. It was still a small circle open to the sky until the very, very end. They used the last of the sandstone chains and then put a giant ring of stone all the way around the top opium. Finally, in 1436, the main structure was finished. They celebrated with huge festivals. But wait, wait, wait, they still had the hole in the middle, right? The oculus. They did, but now they had a surface to build on. Brunelleschi designed a special lantern, a little cupola structure, to sit on top, covering the opening. It took a few more years, but by 1436, the whole exterior was essentially complete. The whole dome used about four million bricks, and the final structure weighed approximately 41,000 tonnes.

SPEAKER_00 8:24

41,000 tonnes? That's heavier than a hundred blue whales. And he did it all without a giant wooden tent underneath him.

SPEAKER_01 8:32

It was the largest masonry dome built up until that point, and it's still the largest one ever built in the world today. Even with all our modern cranes, no one has built a dome this big just out of brick and stone like this.

SPEAKER_00 8:46

So what happened after he finished? Did everyone throw a giant party that lasted a hundred years too?

SPEAKER_01 8:52

They did celebrate. The completion of the dome made Florence the architectural capital of Europe. It proved that humans could achieve anything they set their minds to, which is the whole idea of the Renaissance. It cost about 4,000 gold florins to build, which was a massive investment.

SPEAKER_00 9:11

Did the people who didn't believe him apologize to Filippo Brunelleschi?

SPEAKER_01 9:16

They certainly had to admit he was right. He later designed the beautiful chapel, the Patsy Chapel, in Florence too. It showed everyone that engineering and art could work perfectly together.

SPEAKER_00 9:28

That's awesome! Okay, I need some amazing, weird facts about this dome mirror. Tell me something totally unbelievable.

SPEAKER_01 9:37

Did you know that because the dome is so tall, they actually had to invent new scaffolding and safety rules as they went. If a worker dropped a tool, it could fall over 200 feet. They had to create special nets and rules to stop things from plummeting.

SPEAKER_00 9:54

Nets for dropped hammers? That's so smart. I bet they were terrified of heights.

SPEAKER_01 10:00

Here's another one. The dome is double-shelled, an inner shell and an outer shell, held together by those sandstone chains. The inner shell is actually lighter and thinner, so it doesn't crush the walls. But the outer shell protects it from rain. It's like a giant stone protective egg.

SPEAKER_00 10:19

A stone egg? That's so cool. And it's still there 600 years later. That's like a Lego tower built in the 1400s that hasn't fallen over.

SPEAKER_01 10:29

It really is. It's a monument to one man's big idea and his refusal to believe something was impossible. Alright, Finn, you know all the details about the impossible dome. Time for our quick quiz.

SPEAKER_00 10:42

Okay, okay. I hope I remember the brick pattern.

SPEAKER_01 10:46

First question. What Italian city was home to this amazing construction project? Next one. What was the name of the clever goldsmith who designed the dome? Question three. How many bricks, roughly, did it take to build the entire structure? Here's number four. What amazing machine did Brudleski invent to lift the materials so high. Last question. What special brick pattern did he use so the dome supported itself as it grew? Great job, History Heroes! Let's see how you did. The first answer is Florence, Italy. For question two, it was Filippo Brunelleschi. Number three, the answer is approximately four million bricks. Question four, he invented a new type of reversible crane or hoist. And the final answer is the herringbone pattern.

SPEAKER_00 11:56

Wow, that dome is the coolest thing ever. I still can't believe they built it without the big wooden frame. It was truly impossible.

SPEAKER_01 12:05

It really shows that even when something seems too big or too hard, like that giant hole in the roof, a brilliant idea and a lot of hard work can solve it. It took him from 1420 to 1436.

SPEAKER_00 12:21

If you loved hearing about the giant dome, we really need your help. If you have a moment, would you please ask your grown-up to leave us a five-star review on your podcast app?

SPEAKER_01 12:32

Yes, leaving a review helps other kids who love big architecture, like Charlotte, find our show. Just scroll down and tap the stars.

SPEAKER_00 12:42

Oh, and if you want to see cool drawings of the oxen treadmill crane, or fun facts about the Renaissance, head over to our site kidopoly.com. We have tons of fun learning games there.

SPEAKER_01 12:54

And if you have a question, a historical suggestion, or want a shout out like Charlotte, email us at hello at kidopoly.com. Thanks for travelling with us today. See you next time on History's Not Boring.