Paris, a city of engineering marvels through many centuries
I watched a Discovery Channel documentary called We Built This City: Paris. I found it fascinating.
Paris started out as a small trading settlement on an island in the middle of the river Seine. The location was chosen because it had natural barriers (the river) that made it more easily defensible. After a while, the Romans settled there and built the things you'd expect to find in a Roman city.
The Machine
Fast forward several hundred years, and the city was running out of water. The population had grown, and the river Seine dried up in the summertime. Some monks built some underground aqueducts, but they weren't enough to keep the city well-supplied with water.
In 1866, the City of Paris commissioned engineer Louis-Dominique Girard to solve the problem. About 50 years earlier, Napolean Bonaparte had commissioned another engineer, Pierre-Simon Girard, to build a canal to divert water to the Seine from a nearby river, the Ourcq. Yet even that was not enough. By 1858, navigation along the Canal de l'Ourcq was at a standstill. To bring even more water to the city, Louis-Dominique Girard decided to bring in water from yet another river, the Marne, from even further away, uphill.
Think about that for a moment. As you may have noticed, water flows downhill. When something is downstream, in general it means it is at a lower elevation. Actually water flows from high pressure to low pressure, but pressure is influenced by gravity, so this usually means that water flows downhill in the context of a river.
To move the water uphill, Girard built a hydraulic machine, powered only by two water wheels, no electricity or external fuel needed. It is still in operation today. To say that it is impressive doesn't seem to be quite adequate.
Catacombs
On another topic, after watching the documentary, catacombs now make sense to me. I hadn't really understood why people would dig tunnels under their city and fill it full of the bones of the dead. I didn't think too deeply about it, and when I did, I chalked it up to cultural differences.
The story of how the catacombs of Paris came to exist starts with the building of the Pont Neuf. Its name means literally "The New Bridge". It is now the oldest bridge in the city, but at the time it was created, it was the newest bridge and the name stuck. The bridge was built by order of Henry The Third to increase the accessibility of the central island to the surrounding area, and to deal with a high volume of traffic. In order to make the bridge, people dug tunnels underneath the city and lifted out blocks of limestone from the bedrock. Limestone quarries existed outside the city too, and limestone blocks were mined for building projects such as the Pont Neuf. Limestone is a particularly appropriate building material for bridges because it is resistant to water erosion, having been formed underwater. The Pont Neuf was built over a span of 30 years starting in 1577, during the summer when the river was almost dry. The supporting foundation goes down to the riverbed. This in itself was an innovation at the time.
Fast forward about 200 years, and the city is in dire trouble because of the sheer number of corpses buried in it. Bodies are piled on top of bodies in the graveyards. The air and water are full of poisons from the corpses. The number of corpses keeps increasing because people keep dying from the poisons from the corpses.
Some people decide to solve the problem by removing all of the corpses from the city. Over a period of two years, under the supervision of priests, gravediggers cart the remains of 6 million humans out of the city. But where to put all of those bones?
Outside of the city at the time, though now within the city, was an underground limestone quarry that was no longer in use. This seemed like the perfect place to put the bones. Priests consecrated the tunnels, bones were brought in and arranged, and the catacombs were created!
At the time, it was thought a very dignified resting place for one's bones. The thigh bones were piled into walls a few feet from the tunnel walls, and decorative skulls were added to the wall of bones. The rest of the bones were placed in a loose pile between the thigh bones and the tunnel wall. This paralleled the construction techniques used to create the fortified stone wall around the city, built in 1190-1210 by order of Philippe-Auguste.
The catacombs were built shortly before the French Revolution. Much of Paris as we know it today was built afterward.
Underground Canal
Georges-Eugène Haussmann, commissioned by Napoleon The Third, bought up all of the slums in the centre of the city, demolished them, and created roads and buildings that survive to this day. He is responsible for much of the look and feel of present-day Paris. Before he remade the city, the centre of the city was full of slums with narrow streets. It was very difficult to get from one part of Paris to another. Even visitors passing through Paris noticed this when changing trains, since it was more difficult to travel between the eight train stations in the city than it was to travel to Paris from distant places by train. There were no direct or easy routes between the stations.
Haussmann set out to fix all this. He wanted to make it easy to get around the city. He also had the goal of making it easy to stop riots if they started in the city. This is one of the reasons that there are so many broad avenues in Paris. Those broad straight roads were made to provide easy access for marching soldiers. Indeed military access was so important to him that the idea of building a bridge across a canal in a certain place was abhorent to him because it would cut off the line of sight between the cavalry and the infantry stationed in the city, and provide a choke point where people could more easily build barricades. And yet a way of crossing the canal was needed at that place, so that the infantry could get to the centre of the city. Instead of building a bridge across the canal, or stationing the troops differently, Haussmann decided to put the canal underground for about 2 kilometres! The underground canal is called Canal Saint-Martin. Skylights at regular distances along the canal let air and sunlight in. When I saw the video of what it is like to be a boat travelling down a canal, it reminded me of one of those video games or movies where there's some sort of alien place with spotlights.
The canal, and even more so the streets of Paris have a noticeable beauty to them. We could learn from that, I think. When Paris is designed to prevent riots, it turns out beautiful. Indeed Paris is notably considered to be one of the most beautiful cities on the world. When the Village dorms at the University of Waterloo are designed to prevent riots, they turn out to be grey concrete warrens with narrow hallways that produce a somewhat depressing feel to the place.
Eiffel Tower and Tall Buildings
One of the reasons the Eiffel Tower stands out so dramatically from a street-level view in Paris is that building skyscrapers within the city is prohibited. It was outlawed shortly after a company named Campenon Bernard built a skyscraper in the 1970s that most Parisians hate to this day. There is a special section of Paris, outside the centre of the city, in which skyscrapers and other tall buildings and modern architecture can be built. In this special section are famous modern buildings such as the La Grande Arche. Modern architecture is permitted close to the city centre so long as it is low-rise. Some famous low-rise modern structures include the famous Louvre museum's glass pyramid, and the Centre Pompidou. But most of Paris' modern architecture can be found in the neighbourhood of La Défense.
In the centre of the city, Haussmann built a lot of 4-storey buildings along the avenues he created. They were all exactly 20 metres (66 feet) tall. Haussmann was concerned with making the facade beautiful, and not so much concerned about the interiors. Most of the buildings he built survive to this day. At street level they have shops, and at higher levels they have apartments. Most of the buildings in Paris are about this height.
If for some reason the skyscraper ban was repealed, the height of buildings in Paris would most likely stay about the same. The bedrock, sometimes compared to swiss cheese because of all of the tunneling from the limestone quarries beneath the city, is not strong enough to support the foundations of most skyscrapers. I am used to living in a house where the foundation goes directly into the ground, and the ground is solid beneath it. One of the things that struck me as different about Paris, and indeed about other European cities, is how much is underneath the houses of ordinary people living in the city. If I ever lived there, I think it would be one of the things I would find odd about it. [Update: After writing this paragraph, I surfed the web and found out that the ban on skyscrapers was repealed in 2008, and that a triangular-shaped building will be the first new skyscraper in 30 years.]
Paris is limited by natural features in the directions it can expand. It is bordered by hills, and limited from building higher. From that description you might think that Paris has matured as a city, and that the way it is now will endure for quite some time. From the history of the city's growth as shown in the documentary, it seems to me at least as plausible that it will be totally remade several times over.
Audacity
I've noticed a theme among the developments that I've just recounted. The sheer audacity of the achievements and the fanatical commitment shown to the location of the city astound me. It's like the Parisians said "Oh look. The city is running out of water. We could move to a better location, but no we're not going to do that, let's divert two rivers, one of them uphill, instead!" or "Ooh, we're being poisoned by our own corpses, let's move 6 million human remains!" or "Hey, we could change our military strategy slightly, or we could make the major shipping canal go underground for about two kilometres, so that we have an unobstructed line of sight from the cavalry to the infantry on this particular road!" or "Hey, let's build the tallest building in the world!"
I wonder what they'll do for an encore.
Paris started out as a small trading settlement on an island in the middle of the river Seine. The location was chosen because it had natural barriers (the river) that made it more easily defensible. After a while, the Romans settled there and built the things you'd expect to find in a Roman city.
The Machine
Fast forward several hundred years, and the city was running out of water. The population had grown, and the river Seine dried up in the summertime. Some monks built some underground aqueducts, but they weren't enough to keep the city well-supplied with water.
In 1866, the City of Paris commissioned engineer Louis-Dominique Girard to solve the problem. About 50 years earlier, Napolean Bonaparte had commissioned another engineer, Pierre-Simon Girard, to build a canal to divert water to the Seine from a nearby river, the Ourcq. Yet even that was not enough. By 1858, navigation along the Canal de l'Ourcq was at a standstill. To bring even more water to the city, Louis-Dominique Girard decided to bring in water from yet another river, the Marne, from even further away, uphill.
Think about that for a moment. As you may have noticed, water flows downhill. When something is downstream, in general it means it is at a lower elevation. Actually water flows from high pressure to low pressure, but pressure is influenced by gravity, so this usually means that water flows downhill in the context of a river.
To move the water uphill, Girard built a hydraulic machine, powered only by two water wheels, no electricity or external fuel needed. It is still in operation today. To say that it is impressive doesn't seem to be quite adequate.
Catacombs
On another topic, after watching the documentary, catacombs now make sense to me. I hadn't really understood why people would dig tunnels under their city and fill it full of the bones of the dead. I didn't think too deeply about it, and when I did, I chalked it up to cultural differences.
The story of how the catacombs of Paris came to exist starts with the building of the Pont Neuf. Its name means literally "The New Bridge". It is now the oldest bridge in the city, but at the time it was created, it was the newest bridge and the name stuck. The bridge was built by order of Henry The Third to increase the accessibility of the central island to the surrounding area, and to deal with a high volume of traffic. In order to make the bridge, people dug tunnels underneath the city and lifted out blocks of limestone from the bedrock. Limestone quarries existed outside the city too, and limestone blocks were mined for building projects such as the Pont Neuf. Limestone is a particularly appropriate building material for bridges because it is resistant to water erosion, having been formed underwater. The Pont Neuf was built over a span of 30 years starting in 1577, during the summer when the river was almost dry. The supporting foundation goes down to the riverbed. This in itself was an innovation at the time.
Fast forward about 200 years, and the city is in dire trouble because of the sheer number of corpses buried in it. Bodies are piled on top of bodies in the graveyards. The air and water are full of poisons from the corpses. The number of corpses keeps increasing because people keep dying from the poisons from the corpses.
Some people decide to solve the problem by removing all of the corpses from the city. Over a period of two years, under the supervision of priests, gravediggers cart the remains of 6 million humans out of the city. But where to put all of those bones?
Outside of the city at the time, though now within the city, was an underground limestone quarry that was no longer in use. This seemed like the perfect place to put the bones. Priests consecrated the tunnels, bones were brought in and arranged, and the catacombs were created!
At the time, it was thought a very dignified resting place for one's bones. The thigh bones were piled into walls a few feet from the tunnel walls, and decorative skulls were added to the wall of bones. The rest of the bones were placed in a loose pile between the thigh bones and the tunnel wall. This paralleled the construction techniques used to create the fortified stone wall around the city, built in 1190-1210 by order of Philippe-Auguste.
The catacombs were built shortly before the French Revolution. Much of Paris as we know it today was built afterward.
Underground Canal
Georges-Eugène Haussmann, commissioned by Napoleon The Third, bought up all of the slums in the centre of the city, demolished them, and created roads and buildings that survive to this day. He is responsible for much of the look and feel of present-day Paris. Before he remade the city, the centre of the city was full of slums with narrow streets. It was very difficult to get from one part of Paris to another. Even visitors passing through Paris noticed this when changing trains, since it was more difficult to travel between the eight train stations in the city than it was to travel to Paris from distant places by train. There were no direct or easy routes between the stations.
Haussmann set out to fix all this. He wanted to make it easy to get around the city. He also had the goal of making it easy to stop riots if they started in the city. This is one of the reasons that there are so many broad avenues in Paris. Those broad straight roads were made to provide easy access for marching soldiers. Indeed military access was so important to him that the idea of building a bridge across a canal in a certain place was abhorent to him because it would cut off the line of sight between the cavalry and the infantry stationed in the city, and provide a choke point where people could more easily build barricades. And yet a way of crossing the canal was needed at that place, so that the infantry could get to the centre of the city. Instead of building a bridge across the canal, or stationing the troops differently, Haussmann decided to put the canal underground for about 2 kilometres! The underground canal is called Canal Saint-Martin. Skylights at regular distances along the canal let air and sunlight in. When I saw the video of what it is like to be a boat travelling down a canal, it reminded me of one of those video games or movies where there's some sort of alien place with spotlights.
The canal, and even more so the streets of Paris have a noticeable beauty to them. We could learn from that, I think. When Paris is designed to prevent riots, it turns out beautiful. Indeed Paris is notably considered to be one of the most beautiful cities on the world. When the Village dorms at the University of Waterloo are designed to prevent riots, they turn out to be grey concrete warrens with narrow hallways that produce a somewhat depressing feel to the place.
Eiffel Tower and Tall Buildings
One of the reasons the Eiffel Tower stands out so dramatically from a street-level view in Paris is that building skyscrapers within the city is prohibited. It was outlawed shortly after a company named Campenon Bernard built a skyscraper in the 1970s that most Parisians hate to this day. There is a special section of Paris, outside the centre of the city, in which skyscrapers and other tall buildings and modern architecture can be built. In this special section are famous modern buildings such as the La Grande Arche. Modern architecture is permitted close to the city centre so long as it is low-rise. Some famous low-rise modern structures include the famous Louvre museum's glass pyramid, and the Centre Pompidou. But most of Paris' modern architecture can be found in the neighbourhood of La Défense.
In the centre of the city, Haussmann built a lot of 4-storey buildings along the avenues he created. They were all exactly 20 metres (66 feet) tall. Haussmann was concerned with making the facade beautiful, and not so much concerned about the interiors. Most of the buildings he built survive to this day. At street level they have shops, and at higher levels they have apartments. Most of the buildings in Paris are about this height.
If for some reason the skyscraper ban was repealed, the height of buildings in Paris would most likely stay about the same. The bedrock, sometimes compared to swiss cheese because of all of the tunneling from the limestone quarries beneath the city, is not strong enough to support the foundations of most skyscrapers. I am used to living in a house where the foundation goes directly into the ground, and the ground is solid beneath it. One of the things that struck me as different about Paris, and indeed about other European cities, is how much is underneath the houses of ordinary people living in the city. If I ever lived there, I think it would be one of the things I would find odd about it. [Update: After writing this paragraph, I surfed the web and found out that the ban on skyscrapers was repealed in 2008, and that a triangular-shaped building will be the first new skyscraper in 30 years.]
Paris is limited by natural features in the directions it can expand. It is bordered by hills, and limited from building higher. From that description you might think that Paris has matured as a city, and that the way it is now will endure for quite some time. From the history of the city's growth as shown in the documentary, it seems to me at least as plausible that it will be totally remade several times over.
Audacity
I've noticed a theme among the developments that I've just recounted. The sheer audacity of the achievements and the fanatical commitment shown to the location of the city astound me. It's like the Parisians said "Oh look. The city is running out of water. We could move to a better location, but no we're not going to do that, let's divert two rivers, one of them uphill, instead!" or "Ooh, we're being poisoned by our own corpses, let's move 6 million human remains!" or "Hey, we could change our military strategy slightly, or we could make the major shipping canal go underground for about two kilometres, so that we have an unobstructed line of sight from the cavalry to the infantry on this particular road!" or "Hey, let's build the tallest building in the world!"
I wonder what they'll do for an encore.