All these underwater cities/buildings could be BS from being flooded underwater naturally.

Have you guys seen Paris underground cavern? There was another documentary about a Cathedral which I don't remember what it is called. But, in one line they said "they had to put rocks underneath the cathedral to stop it from collapsing." It had an underground cavern with a very deep hole that you can see water from the lake/river. It was said they got the stone from there to build the cathedral itself. There is probably a reason why many newly discovered cities are underwater.

Where do you think we get the rocks from? Earth of course. We dig up the rocks and build the buildings, walls and towers. This of course makes the land vulnerable to sinking. Especially, if you place your buildings where you dig the rocks from like that cathedral I was talking about.

This is one reason why some ancient buildings like China's great wall or Greek buildings isn't underwater. The Great Wall is built on top of the mountains, and the Greek buildings were built on top of hills. The rocks came from else where. If you dig a hole deep enough underground and put heavy stuff on top of it, it will collapse and sink.

There is probably a reason why many civilizations or walls are buried underground or collapsed into the ocean. It is like the some sewers, you dig too deep, the ocean/lake water has access to the tunnel easily. Therefore, can flood the tunnel due to the same ground level. With heavy buildings on top, it will have a chance to collapse the tunnel bringing the buildings down with it.

Building built on limestone have the trouble of acid rain eating away at the limestone causing cavities, ancients did not have that worry, volcanic activity has gone up three hundred percent in the last two thousand years, thereby ejecting all sorts of acidic gases into the atmosphere, which combine with rain to produce the acid.
I doubt the ancients would be stupid enough to build over a hole, the pyramids spring to mind...

a reply to: makemap

If you look at the construction of Nan Madol you will see that the ancient peoples had incredible knowledge ands ability - probably more than we have today even - in the handling of building in watery places and allowing for increases in the water levels.

I do see erosion as you rightly put it, but not on the scale you say. Surely under water cities happen because the water table on this planet alters in accordance with hoow much water is held in ice which slowly varies as the sea levels in the past demonstrate. Look at alexandria with its lighthouse now under water yet the city is above and thriving. Also Dogger is another example where the water simply overrun the land as the water table came higher.

a reply to: makemap

You logic is impeccable. Dig rocks up, (somehow) build something on top of that void, and you eventually you have sunken buildings and maybe even flowing water or a lake underneath as you presented in the Paris cathedral instance. I wonder why the early builders never thought of those shortcomings?

If you ask Google for a picture of the Great Wall of China ending its way into the sea, I'll bet you can find it. I don't know if there is a hill or mountain under that beach, maybe.

a reply to: makemap Do you have any examples of cities that are underwater with evidence that they sank because the were built over a quarry [somehow]? Do you understand that the ocean levels have risen since the last ice age? Can you guess how far? Do you understand that subsidence of land also occurs but not just over a quarry?

originally posted by: Shiloh7
Surely under water cities happen because the water table on this planet alters in accordance with hoow much water is held in ice which slowly varies as the sea levels in the past demonstrate. Look at alexandria with its lighthouse now under water yet the city is above and thriving. Also Dogger is another example where the water simply overrun the land as the water table came higher.

Part of ancient Alexandria is submerged, but not because of a rise in sea level. The place sank, like what happened at Port Royal in Jamaica. Lots of places like that around the Mediterranean.

There has never been a submerged city found that was overwhelmed by rising sea levels.

Not that there aren't archeological sites like that. Just not cities.

Harte

Over long time periods the face of the Earth undergoes many changes ... Where there was land becomes sea bed and where the sea once was becomes new land ... Look at mountains of South America that contain sea fossils thousands of feet above sea level ... all is constantly changing over vast time periods ...

We have witnessed upheavals of Earth many times through out Human history ... perhaps we have yet to witness them in this present time in terms of Biblical proportions so to speak ... Nothing last forever for everything must change ... Even the Earth will be no more one day

I believe that other highly advanced civilisations have existed before this one ...