Hi and welcome to the forum.
It is my opinion, that Atlantis, as described by Plato, did not exist. It is my contention that he took a number of things he knew of, and a number of things he'd like to see happen, and incorporated them into what he felt would be a perfect arrangement. Plato was not a well traveled man and it seems Solon only traveled late in life, so neither one of them actually saw much of the world.
In my own thread, Plato's Atlantis My Theory, I have posted pictures of the Plains of Thessaly, which in my opinion, were the inspiration for the description of the lay of the land. For the circular rings, I think he or Solon, may have been told by the Egyptians about the salt rings that show up in different places in N. Africa, the most famous one being the Richat structure.
Plato
Looking towards the sea, but in the centre of the whole island, there was a plain which is said to have been the fairest of all plains and very fertile. Near the plain again, and also in the centre of the island at a distance of about fifty stadia, there was a mountain not very high on any side. In this mountain there dwelt one of the earth born primeval men of that country, whose name was Evenor, and he had a wife named Leucippe, and they had an only daughter who was called Cleito.
.....................The whole country was said by him to be very lofty and precipitous on the side of the sea, but the country immediately about and surrounding the city was a level plain, itself surrounded by mountains which descended towards the sea;
Plains of Thessaly
I would say this looks a lot like what Plato was describing. It's the Plain of Thessaly. Something he would likely be familiar with and something that could have inspired the description of his Atlantis.
......the city was surrounded by a uniformly flat plain, which was in turn enclosed by mountains which came right down to the sea. This plain was rectangular in shape, measuring three thousand stades in length and at its midpoint two thousand stades in breath from the coast.
The Plains of Thessly, Greece
P.S.
Why did you choose to post this topic in the coffee shop? There's lots of threads under the title of Atlantis.
