It's Written in the Concrete

Though the Romans have a pretty impressive reputation, in many regards they weren't nearly so clever as people tend to think they were.

For example, their fabled legions, while effective early in Roman history, became rather useless toward the end: the knight was basically invented by barbarians looking to defeat Roman legions. Even after it became apparent that the legions were a tool of the past, the Romans foolishly just kept sticking with it.

However, one area in which they were unquestionably brilliant was in architecture and construction.

Much has been made of Roman aqueducts and other construction techniques, but one technology that doesn't get discussed nearly as much as it should is their concrete. Roman concrete—known as opus caementicium—is, interestingly, much more durable than modern day concrete.

We have many examples of Roman concrete that have survived all the way to today. The Pantheon in Rome (not to be confused with the Parthenon), for instance, is a concrete dome that has survived intact since 126 AD.

Even more impressive is Roman concrete's resistance to seawater. Seawater is incredibly corrosive to modern buildings, corroding and destroying them in mere decades. We're lucky to get 50 years out of modern concrete. Roman concrete, however, can survive immersion in seawater for centuries or even millennia; plenty of docks and pilings from Roman times can still be found off European shorelines.

What was their secret? Well, we don't know the exact composition of Roman concrete, but we do know one of the major secrets: they used volcanic ash instead of the fly ash we use today. When submerged in seawater, the seawater reacts with the mineral phillipsite, found in volcanic ash. Over time, a new mineral known as tobermorite forms in the cracks of the concrete. As it forms, the concrete actually gets stronger and stronger.

Roman concrete today is stronger than when it was first laid down.

Many people are trying to mimic Roman concrete today. Not only is it more durable and long lasting, but it's also cheaper and more environmentally friendly. The problem, of course, is the extremely long setting time: most builders don't want to wait long enough for Roman concrete to set.

Haste makes waste. Some people are okay with that. Roman concrete endures.

Going Dutch

The Dutch are, without a doubt, the most impressive hydrological engineers on the planet.

You really have to be when much of your country lies below sea level and is vulnerable to floods. I could spend blog post after blog post talking about how impressive the Dutch are at what they do, and I might just do so at some point. For now, though, I'm exploring one of the most innovative pieces of hydrological engineering they created: the Dutch Water Line.

The Dutch Water Line was a series of defenses built to flood huge chunks of the Netherlands (then Holland) if invading forces threatened. Engineers first dreamed up the idea in the early seventeenth century and built it quickly afterward.

The idea didn't appear from thin air (or, er, shallow water). The Dutch eighty-year war of independence against Spain featured several instances of flooding used as a defense. Yet, building out this new concept—to cut off all of Holland was a much larger and more ambitious step forward. The Dutch finished the line in just a few short years. Which brings us to the early 1630s.

Less than four decades later, strategists first tested Dutch Water Line during the Franco-Dutch War, also known as the Third Anglo-Dutch War. (Keeping track of European wars is an exhausting and unrewarding task that I've never bothered to pursue, except in reference to more interesting parts of history.)

Me, Getting Smarter by the Sip

Fun fact: We have coffee to thank for economics, geology, and countless other scientific and intellectual advancements.

Seventeenth century Scotland was a nasty place in many ways, filled with poverty, disease, and chronic alcoholism—in great part because the water wasn't safe to drink. Raids from highland clans were also a fact of life.

By the eighteenth century, however, things had changed radically. The highland clans were defeated, the economy was looking up, and things were just improving all around.

And then coffee showed up.

All of a sudden, you had something to drink that would neither make you sick, like the water, or drunk, like the ale.

Intellectuals started gathering in social clubs and became massively more productive. Among those intellectuals were Adam Smith, the father of modern economics; James Hutton, the father of modern geology; Robert Burns, one of the greatest English language poets of all time (as well as Scots language poets); Joseph Black, the chemist who discovered magnesium and carbon dioxide; philosopher David Hume; and many more.

What's more, they weren't operating alone. They largely all knew one another. Joseph Black, James Hutton, and Adam Smith were all incredibly close friends.

This was a movement focused on empiricism and reason, and it came to be known as the Scottish Enlightenment.

These changes weren't just limited to Scotland, either. Everywhere coffee traveled, there tended to be increases in productivity, intellectual development, and general economic well-being of a nation (though not necessarily for individual members of a nation.)

Coffee is by no means an unadulterated good in history, especially not at the growing end of the supply chain, but it did radically change history wherever it arrived.

Pretty impressive for a beverage.

The Turkish Underground

The Cappadocia region of Anatolia, Turkey, is riddled with underground cities. In 1963, a man in the region knocked down a wall of his home (for home renovations, I hope, though maybe he was just in a particularly bad mood) and discovered a mysterious room built into the rock.

After a little more digging, he broke into a whole intricate tunnel system: the Derinkuyu underground city, carved thousands of years ago.

The Cappadocia region sits on a one kilometer (3,300-foot) tall volcanic plateau. Millions of years ago, it was covered in volcanic ash, which solidified into tuff, a type of volcanic rock.

That made for easy digging, and the inhabitants of the region some 3,000 years ago quickly took advantage of this to dig their elaborate tunnel cities. (Not all tuffs are soft and easily dug into, however; some tuffs are extremely tough.)

People developed a wide range of uses within the tunnel systems. Food storage was one of the earliest and most reliable: cave systems tend to maintain constant temperatures, often considerably cooler than the surface.

We’ve also used underground cities multiple times throughout history to hide from attack. Derinkuyu is extensive enough that it could have hidden as many as 20,000 people. They had the benefit of ample storage space, which included wine and oil presses, stables, refectories, and chapels.

The city contains five different levels, each of which could be closed off independently of the others. Not least incredibly, the Derinkuyu is also connected to the Kaymakli underground city by an 8 km (5 mile) underground tunnel.

There is some debate about who first built the cities. Some attribute them to the Hittites (between the 15th and 12th centuries BC), but most believe they were constructed by the Phrygians (between the 8th and 7th century BC), the people who supplanted the Hittites, and then themselves faded away during Roman times.

The Derinkuyu was used by the Byzantines much later to defend themselves during the Arab Byzantine wars (780-1180 AD). Even as late as the early 20th century, the tunnels were still in use by the locals to avoid Ottoman persecution, only falling into disuse in 1923. So, doing our math, the lost city had only been lost for 40 years when it was re-found.

Today, much of the Derinkuyu underground city is open for visitation by tourists. And more than 200 other underground cities with a minimum of two levels (40 have three or more) have been discovered in the region.