What was the first road?

0:00 Welcome to History's Not Boring by Codopoly.com. I'm Mira. And I'm Finn. Before we begin, a massive shout out to Poppy, who is six, and her brother Simon, who is four. They live in Salt Lake City, Utah, and they love listening to us in the car. And a big hello to ten-year-old Zane, listening in Winnipeg, Manitoba, Canada, who asked all about the history of cakes.

0:24 Poppy and Simon asked how the very first roads were made, which is exactly what we're talking about today. So Zane, just imagine roads as a giant stony layer cake. Oh, and if you haven't already, tap follow wherever you're listening so you never miss an episode. Alright, Finn, prepare your brain. Did you know that the ancient Romans built enough roads to circle the entire Earth ten times?

0:54 Wait, ten times? That's like running around the whole planet, through the oceans and everything, ten times over. Exactly! They built an incredible 400,000 kilometres of roads. But for most of human history, there was absolutely nothing to drive or walk on except squishy, sticky mud. Ugh, my shoes are getting dirty just thinking about it.

1:19 Today we are travelling from ancient muddy tracks to cobblestones to the smooth roads we drive on now. This is the story of how humans paved the world. So if there were no roads, how did people get anywhere? Did they just wander through the forests? Pretty much. Early humans just followed animal trails.

1:40 Imagine walking barefoot on a dirt path that turns into a slippery, stinky mudslide every time it rains. Ew! Mud and animal poop between my toes. No thank you. People got sick of the mud. About 5,800 years ago in England, a group of early farmers decided to build a path across a massive, squishy swamp called the Somerset Levels.

2:07 A swamp path? How did they build that? They chopped down massive oak trees and built a wooden walkway. It's called the Sweet Track. They drove long wooden poles deep into the soggy marsh in an X shape and then laid heavy, flat oak planks across them. It was a little over a mile long. That's actually really smart.

2:30 No more swamp water in your boots. Exactly, but wooden roads rot eventually. If we want to find the world's oldest known paved road, we have to travel to ancient Egypt, about 4,600 years ago. Oh, pyramids and pharaohs. Yep, they needed to move massive, heavy volcanic rocks called basalt from a quarry to a lake.

2:55 So they built the Lake Morris Quarry Road, about 50 miles southwest of Cairo. How do you actually pave a road back then without concrete? They laid down pieces of petrified wood and heavy flat stones to make a raised platform. It was tough enough that giant sleds carrying rocks weighing thousands of pounds could slide right over it.

3:18 Whoa, so it was like a superhighway for heavy rocks. I bet the workers were glad they didn't have to push those through the mud. Oh, definitely! But the true masters of road building were the ancient Romans. About 2,000 years ago, their empire was growing fast, stretching across Europe, Africa, and the Middle East.

3:38 Let me guess. Marching through mud wasn't working out for them. Not at all. A Roman army legion had over 5,000 soldiers. Marching in deep mud slowed them down. So the Roman engineers invented a completely new way to build. Haha, was it Zane's cake? Did they build a cake road? Kind of. They built their roads in four distinct layers, just like a giant stony cake.

4:06 First, they dug a trench about three feet deep. That's up to my waist. That's a lot of digging. Then, for the bottom layer, they packed in large heavy rocks to make a solid base. They called this the statumen. Okay, layer one down. What's next? Layer two was a mix of smaller stones, gravel, and a special concrete made from volcanic ash.

4:31 It was called the Rudus. Volcanic ash concrete? That sounds indestructible. It almost was. Layer three, the nucleus, was made of fine sand and crushed brick packed tightly together. And the frosting on the cake? The top layer, the summum dorsum. These were massive, perfectly cut slabs of hard rock, fitted together so tightly you couldn't even slide a knife between them.

4:57 Whoa! So you have big rocks, concrete, sand, and paving stones. That is a seriously tough road. It gets even better. The Romans knew that water destroys roads, making them sink or crack. So they designed their roads with a slight curve in the middle, like a turtle shell. Oh, so when it rained, the water would just roll right off the sides.

5:20 Exactly! That curved shape is called a camber. The water ran off into deep drainage ditches dug on both sides of the road. Those Romans thought of everything. No puddles. They really did. And because these roads were so smooth and well built, the Roman soldiers could march over 20 miles in a single day.

5:42 That would take forever in the mud. Did they have road signs so they wouldn't get lost? They did. They invented milestones. Every single mile they placed a large stone pillar, weighing thousands of pounds, telling travellers exactly how far they were from the nearest city. Like a heavy stone GPS? Yes.

6:03 And in the very centre of Rome, the Emperor Augustus placed the golden milestone. It was a monument, and every distance in the entire empire was measured from that exact spot. Is that where the famous saying, all roads lead to Rome, comes from? It sure is. Their network was so massive that no matter which road you took, it would eventually connect back to the capital city.

6:28 One of their most famous roads, the Via Appia, was started in 312 BC. Wait, people are actually driving modern cars on some of those foundations today. That's mind-blowing. It is! But building Roman roads was incredibly expensive and took tens of thousands of workers. For hundreds of years after the Roman Empire fell, road building kind of just stopped.

6:56 Back to the mud puddles. Sadly, yes. Until the early 1800s, when a brilliant Scottish engineer named John Loudoun McAdam came along. He realised roads didn't actually need massive, heavy stone slabs to be strong. What did he use instead? He used layers of small, crushed, angular stones. He actually had a rule for his workers.

7:21 No stone could be heavier than six ounces or larger than two inches wide. Why so small? Because when heavy horse carriages rolled over them, the jagged edges of those small stones locked tightly together, creating a hard, solid surface. Like puzzle pieces squished together. Exactly. And his roads were sloped for drainage, just like the Romans did.

7:46 His invention was so revolutionary, they called these roads Macadam roads. Macadam? That sounds so familiar. Have you ever heard the word tarmac? Yeah, like out on the airport runway. Well, later on, engineers realised that cars were kicking up too much dust on Macadam roads. So they started pouring sticky black tar over the stones to seal them.

8:12 Tar plus macadam equals tarmac. Oh my goodness, that makes so much sense. And here's one last weird fact from ancient times. In Roman cities, the roads got really dirty from horse wagons, so they built huge stepping stones right across the middle of the street. Stepping stones? Like for crossing a river.

8:34 Yep. Pedestrians could cross the street without stepping in the smelly horse muck. And the chariot wheels were spaced perfectly to roll right between the stones. OK, avoiding horse muck is definitely the greatest historical invention of all time. Alright, Finn, time for the quiz. You ready? Okay, I'm ready.

8:54 Bring on the questions. First question. What was the name of the 5,800-year-old wooden trackway built across a swamp in England? Next one. What country has the oldest known paved road, which was used to move heavy rocks? Question 3. The Romans built enough roads to circle the earth how many times? Here's number four.

9:29 What was the curved shape of a Roman road called which helped rain run off? Last question. What modern road material gets its name from a Scottish inventor named Macadam? Great job! Let's see how you did. The first answer is it was called the sweet track. For question two, the oldest paved road is in Egypt.

9:59 Number three, the answer is they built enough to circle the earth ten times. Question four, the curved shape is called a camber. And the final answer is the material is called tarmac. Man, I will never look at the road the same way again. To think it all started with squishy swamp logs. Next time we're in the car, just imagine those four layers of Roman stones under the tyres.

10:27 Hey, if you're listening and you love history as much as we do, please give us a five-star review. Maybe tell us what you would name your very own road. Just scroll down in your podcast app and tap the five stars. And don't forget to tap follow so new episodes turn up on their own. Oh, and we have sister shows too.

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