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| · | Why Are Cities Built on Top of Each Other? |
| 0:00 | · | This is what the Roman Forum looked like in 1864 |
| 0:04 | · | and this is what it looks like today. |
| 0:06 | · | When archaeologists started digging here |
| 0:08 | · | they uncovered an entire world of ruins deep underground |
| 0:11 | · | that hadn't been seen for centuries. |
| 0:14 | · | Over time, the city had risen by more than 10 meters |
| 0:17 | · | and older buildings had been completely forgotten about. |
| 0:20 | · | All over the world you'll find ruins |
| 0:22 | · | that are slowly being left behind by the constant rise of the streets |
| 0:27 | · | and modern cities that have been built on top of old ruins. |
| 0:31 | · | The ancient city of Troy was rebuilt 10 times forming 10 distinct layers |
| 0:36 | · | all built directly on top of each other. |
| 0:39 | · | Even the city of Seattle has an entire network |
| 0:41 | · | of mysterious, abandoned shops and houses |
| 0:44 | · | buried beneath the modern streets. |
| 0:46 | · | But why are cities built on top of each other? |
| 0:49 | · | Is the street level actually rising? |
| 0:51 | · | and why does history always end up buried deep underground? |
| 0:55 | · | We modeled the entire thing |
| 0:56 | · | to show you how civilizations build on top of each other. |
| 1:00 | · | We'll also look at the crazy historical layers beneath Rome, |
| 1:03 | · | these strange hills all over the Middle East, |
| 1:06 | · | and the mysterious city purposefully buried beneath Seattle |
| 1:09 | · | over 100 years ago. |
| · | What's Beneath the Basilica of San Clemente? |
| 1:11 | · | There is no single reason why cities are built on top of each other. |
| 1:15 | · | After the great fire of Rome in the first century |
| 1:18 | · | most of the city had to be rebuilt. |
| 1:20 | · | But instead of clearing away the rubble |
| 1:21 | · | it was quicker and easier to simply flatten it out and build on top. |
| 1:25 | · | This meant that new buildings were about a meter higher than the street. |
| 1:30 | · | And so, to match the new height |
| 1:32 | · | the streets were raised and resurfaced |
| 1:34 | · | using rocks from the surrounding debris. |
| 1:36 | · | With every fire and natural disaster that occurred, this process would repeat itself |
| 1:41 | · | raising the city and leaving old ruins buried underground. |
| 1:44 | · | One of the clearest examples of this |
| 1:46 | · | is the Basilica of San Clemente in Rome. |
| 1:49 | · | The structure we see today is from the 12th century |
| 1:52 | · | but it was built directly on top of an old church from the 4th century. |
| 1:57 | · | That church was built directly on top of a mysterious old temple |
| 2:01 | · | and that temple was built on top of an old house. |
| 2:04 | · | And there are even older ruins beneath that. |
| 2:07 | · | All in all, the valley in which San Clemente lies |
| 2:10 | · | is now 18 meters higher than it was in the first century. |
| 2:14 | · | Here's what happened. |
| 2:15 | · | Back in 1st century Rome, before the Colosseum was built |
| 2:19 | · | a Roman villa sat at the bottom of the valley. |
| 2:22 | · | After being damaged in a fire |
| 2:23 | · | it was converted into a temple by the Mithra people |
| 2:26 | · | a mysterious cult which was gaining popularity throughout Rome. |
| 2:30 | · | But by the end of the 4th century |
| 2:32 | · | the temple was partially destroyed by the Christians. |
| 2:35 | · | Looking to promote their religion, they decided to build a new basilica |
| 2:39 | · | on top of the old temple. |
| 2:41 | · | This basilica served the Christians for another 800 years |
| 2:45 | · | But by the 12th century it fell into disrepair. |
| 2:48 | · | After multiple fires and rebuilds around the basilica |
| 2:52 | · | the street level had risen considerably |
| 2:54 | · | and so instead of knocking it down a new basilica was built on top. |
| 2:59 | · | This is the one we see today. |
| 3:01 | · | Eventually, the ruins beneath the basilica were filled in |
| 3:05 | · | and because no one kept track |
| 3:06 | · | all knowledge of the previous layers was completely lost. |
| 3:10 | · | But in the 1800s, an archaeologist started digging |
| 3:13 | · | and unearthed the old basilica |
| 3:15 | · | with a staircase leading down to the first century temple. |
| 3:19 | · | Inside was a Mithra shrine |
| 3:21 | · | and scrolled on the walls were paintings dedicated to the Mithra God |
| 3:25 | · | [ad text redacted] |
| · | Artificial Hills (Tells) Explained |
| 4:48 | · | We've seen how Rome is built almost entirely on old ruins |
| 4:52 | · | but one of the best examples of a layered city |
| 4:55 | · | dates back to a time long before Rome ever existed. |
| 4:59 | · | All over the Middle East |
| 5:00 | · | you'll find these strange looking hills with mysteriously flat tops. |
| 5:04 | · | These are known as tells. |
| 5:06 | · | Tel as in Tel Aviv, which used to look like this. |
| 5:10 | · | These are artificial hills formed by centuries of civilizations |
| 5:15 | · | building on top of each other. |
| 5:16 | · | Inside each tell is a world full of old ruins lost in time. |
| · | The Ancient City of Troy |
| 5:22 | · | Perhaps one of the most impressive of these is the ancient city of Troy |
| 5:26 | · | which first began as a small settlement back in 3000 BC. |
| 5:31 | · | The buildings were mostly made from mud bricks |
| 5:34 | · | and when they were destroyed the material decomposed |
| 5:37 | · | and covered the ruins and soil |
| 5:39 | · | then a new settlement came along and built on top. |
| 5:42 | · | Over the following millennia, eight more civilizations took over this mound |
| 5:46 | · | going from the Persians to Alexander the Great, and eventually the Romans. |
| 5:50 | · | Up until the year 500 AD |
| 5:53 | · | when the nearby port dried up and the last civilization left the city. |
| 5:58 | · | Eventually the buildings crumbled back into the hill |
| 6:01 | · | and the soil took over, making Troy a complete mystery |
| 6:04 | · | until it was discovered in the 1800s. |
| 6:07 | · | In most cases humans are the main cause of layered cities |
| · | Sinking Cities: Shanghai |
| 6:11 | · | but there is something we haven't talked about yet. |
| 6:13 | · | What happens when buildings and cities literally sink into the ground? |
| 6:18 | · | Did you know that Shanghai is currently sinking |
| 6:21 | · | by around 1 cm every year? |
| 6:23 | · | In fact, most major cities across China are all sinking. |
| 6:27 | · | For centuries, the only way to get fresh drinking water |
| 6:30 | · | was to pump it out of the ground |
| 6:32 | · | but by doing this, the pores that hold the water are emptied |
| 6:35 | · | causing the ground to compress and sink. |
| 6:38 | · | This is a problem all over the world, but the soil beneath Shanghai |
| 6:41 | · | is particularly soft and with the sheer weight of all the skyscrapers sitting on top |
| 6:46 | · | the city has shrunk around 3 meters in the last century. |
| 6:50 | · | When cities sink too much they fall below sea level |
| 6:53 | · | and end up completely lost. |
| 6:55 | · | The only real solution to get above the water is to build on top. |
| 6:59 | · | That is exactly what happened in Seattle. |
| · | Seattle's Underground City |
| 7:02 | · | Although Seattle is only 175 years old, it already has an entire network |
| 7:07 | · | of streets and abandoned buildings hidden beneath the modern city. |
| 7:11 | · | In 1889 a devastating fire ripped through the newly formed city |
| 7:16 | · | and, just like Rome, almost everything had to be rebuilt. |
| 7:20 | · | The mayor took this as an opportunity to drastically improve the city's design |
| 7:25 | · | which already had huge problems with flooding. |
| 7:27 | · | The idea was to raise the entire city |
| 7:30 | · | and install drainage pipes underneath the streets |
| 7:33 | · | allowing the water to naturally flow out to the sea. |
| 7:36 | · | To pull this off |
| 7:37 | · | 6 meter high stone walls were built on either side of the streets |
| 7:41 | · | and roads were built on top. |
| 7:44 | · | For a while, Seattle went through a weird phase |
| 7:46 | · | with its buildings sat two stories below street level |
| 7:49 | · | and people had to descend on ladders to get to shops and houses. |
| 7:53 | · | Eventually the gaps were filled in and proper sidewalks were installed |
| 7:56 | · | leaving behind a well preserved city right beneath Seattle's streets. |
| 8:02 | · | And now, time for the Primal Space Giveaway. |
| 8:04 | · | The winner of the previous giveaway is Jimmy! Congrats. |
| 8:07 | · | In the next video we'll be giving away another $100 Amazon gift card to one lucky viewer. |
| 8:13 | · | All you need to do is sign up at the link below |
| 8:16 | · | like the video, and leave a comment saying what you think of these amazing underground ruins. |
| 8:22 | · | Thank you very much for watching and I'll see you in the next video! |
