This was known from the ancient world so those Egyptians priests that talked to Solon the Athenian and Plato is telling us the Story through Timaios and Critias dialogs, knew the difference between those to places/empires.
Also in the dialogs the egyptian priest is talking about another Athens... not the same as the days of Solon.That Athens were located near nowdays Boitia. Another point is that the location of Atlantis was outside the Hercules pillars... nowdays Gibraltar. Both places were destroyed by mother nature... Atlantis in a night... Hegeys in few years as a cause of the floods during the ice-melting (4 of em in Greek Mythology, historians believe that the 1st one vanished Hegeys).
I know that all these sound as a fairytale but in ancient greek, "mythology" comes from "μυθω/μυω" (=Mytho/Myo, im wispering something to the initiates) and "Λόγος" (=Logos,the way to express our thoughts, speak), so it's a story that only those who are initiates will understand, a code.That's why fairytale in greek is "παραμύθι" wich means Not-a-myth.
I believe the dialogues described Athens as where it is today.
Now the city in those days was arranged on this wise. In the first place the Acropolis was not as now. For the fact is that a single night of excessive rain washed away the earth and laid bare the rock; at the same time there were earthquakes, and then occurred the extraordinary inundation, which was the third before the great destruction of Deucalion. But in primitive times the hill of the Acropolis extended to the Eridanus and Ilissus, and included the Pnyx on one side, and the Lycabettus as a boundary on the opposite side to the Pnyx, and was all well covered with soil, and level at the top, except in one or two places