From the official point of view, the ruinist artists had a very developed and violent imagination, they invented destroyed structures from their heads, and the fact that they did it all in a row was because it was fashionable.
But not everyone believes in the official point of view, many do not believe that they drew something that is not, but assume that they drew reality.
Looking at Piranesi's paintings, clarity of graphics, meticulousness in details, the thought comes latently that this is not just an artist, but a person who set out to capture and leave it for history.
If the ruins are real, what could have caused such destruction? Here are some versions of what might have happened:
Antediluvian - as the term probably began to be used after this flood. The flood version is one of the most popular.
The flood could occur from the fall of a large cosmic body into the world's oceans, as a result of which a multi-meter wave rose and burst onto land with great force, destroying everything in its path and flooding entire countries. Then the wave gradually lost its strength and the water began to partially recede somewhere, but all the water could not quickly disappear. Most likely, there are cities that still lie under water.
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It was a nuclear bombing! Thousands of tons of soil rose into the air in the form of dust and soot and settled on cities. Water has nowhere to come from in such quantities. They hid it because no one would demand the right to land. The states were different. Mammoths died out not millions of years ago, as scientists did, because in Yakutia they are taken out of the ice and dog meat is eaten.
People in the paintings look ridiculous, too small compared to the ruins, hence another version.
No people returned anywhere. The tiny figures look completely ridiculous against the backdrop of giant windows and doors. These buildings were built by someone else, larger. And most likely this civilization has perished. Where did modern people come from, I do not know, whether from the forests in which they hid, whether they descended from the mountains.
Judging by the drawings, the civilization was developed, they could manipulate huge blocks in construction, they had a water supply system that was still working after what happened, judging by the drawings, and then there were explosions of something technogenic - apparently the remnants were burning.
And then, on the ruins of the old civilization, a new life began, but in history there was a cleanup of those events, the authors were declared dreamers, the paintings were renamed, the books were burned. 200-300 years have been thrown out of history.