Plato’s story of Atlantis is almost certainly fictional. In Arcadian folklore, however, there is a kingdom of the same name. Although the Platonic Atlantis is imaginary, Plato arguably based it (in part) on the Arcadian Atlantis which has a real geographical setting; the Arcadian town Methydrium (‘Between the Waters’). The Arcadian king list likely inspired Plato’s kings of Atlantis meaning the Platonic Atlantis is a pseudomythology. In this paper, the Arcadian-Atlantis hypothesis is defended against criticisms, namely that the Arcadian Atlantis was a Hellenistic period invention. The Arcadian Atlantis or kingdom of Atlas – is revealed to be a real place (Methydrium) in the Peloponnese, but which today lies in ruins