Lost Civilization: There were "Photos" of how the world died in the 18th century

We are all familiar with the numerous paintings by Giovanni Battista Piranesi, but modern historians explain his engravings with vivid fantasies of the author.
Many viewers, however, have already realized that this artist and many others depicted exactly what they saw with their own eyes — the ruins of European cities destroyed in the middle of the 18th century.
Naturally, many questions remain: Who were these artists,
where did they learn to draw and where did they come from in these recently destroyed cities?

What happened to the residents of these cities? How did the same ruin artists survive? My opinion is
that urban violence was eradicated before the flood and was destroyed by the war.
The artists who arrived here a few decades after the flood originally lived somewhere in the mountains somewhere in the mountains and therefore survived,
then they came to the ruins of the cities and later inhabited them.