Welcome Puzzler,
I believe Atlantis does not exist physically at all, believe me, I thought it did for ages but now don't... and did not sink but he is talking about a collective notion of a previous civilization that can be found over and over that 'sinks' as such as we lose any knowledge of it, allegory of the traveller not being able to get there anymore...he introduces Critias as such...like a weary traveller....Troy is ideal example and is probably one connotation of his Atlantis. I do believe however that he has placed it in context of being an island in the Atlantic such as the Greeks saw the island that Hera came from in the West. If you read Book 3 of The Laws you can see the same ideas he brings forth in the Atlantis story placed into a real context, almost like a proto-type of his idea.
Not entirely unlikely.
OK, but anyways, consider this, true fact...Columbus read some work by Aristotle who had claimed that if you sailed West it would bring you back around to the East..as it does and Columbus, spurred on by this thought did exactly as Aristotle said and also was convinced he had reached The East Indies as we all know...Aristotle also tells us Plato created Atlantis just to sink it and was not a believer of it, now if anyone would know, I reckon it was Aristotle, since he was the closest student to Plato we know of...
the consideration is this...they both knew the world was round, it was put forth by this time but shot down in flames but Plato was no dummy, of course he knew the world was round, he was too astronomically educated not too...
So, consider a round Earth with the known continental area as one...to get to the other side (the opposite side) you would go out West....thru the Pillars, the island Hera came from is there according the the Greeks, which I see as Atlantis, Herodotus in 450BC which is a read you have to read if you have not...he calls the Atlantic Ocean, the Atlantis Sea, so you travel West still past 'Atlantis' in the Atlantis Sea, keep sailing and where would you end up if you did not know the Americas were there...the opposite side of the Continent of course....just as Columbus thought he had done....the boundless continent. Well, that's my views after endless readings and decipherment of it all, you may find it interesting....

This is an interesting take on the boundless continent, but there are a couple of things that seem problematic. This concept of a lone disk-shaped world composed of Europe, Libya and Asia surrounded only by ocean on a spherical earth might more likely draw the description of a continent bounded by the sea rather than a sea bounded by a continent. Keep in mind that this boundless continent was referred to as 'the surround-ING land' as opposed to 'the surround-ED land'. Of course a miscalculation of the earth's circumference similar to the one Columbus maintained, might attain the reversal of roles you are looking for.
However, Solon was contrasting the Mediterranean as a sea ALMOST surrounded not by one, but THREE separate continents having just named two of them, Libya and Asia. Why would he in the same breath suddenly switch and refer to the world as one continent and boast that it surrounds the true ocean when he had just confirmed that this same THREE continent combination did not even completely surround the much smaller Mediterranean?
PS: All ancients believed in Troy, none doubted it at all, it was part of their true history....only modern interpretations changed that..somewhere along the way we disbelieved it but no ancient did, probably because like Plato tells us we all just forgot about it and the knowledge of it was lost through time, it was always there to them.
You make a great point. Modern-day scholars discarded a literal Troy because it did not fit
established history, something that actually is prone to change with the latest unearthed findings and the subsequent whims of men. In spite of this, Schliemann pursued the location placing the highest priority on the most basic element of the Trojan saga, the recorded geographical details and other aspects which remain the most physically tangible over time, and in so doing successfully discovered the city. South America as Atlantis may not fit academia's historical view either, but geographically it's the best fit and is too precise to ignore. If you haven't had a chance you may wish to review the main portion of the article which details the geographical similarities of Atlantis and South America:
Atlantis: The Land Beyond The Pillars.
-Doug