Atlantis (Ancient Greek: Ἀτλαντὶς νῆσος, romanized: Atlantìs nêsos, lit. 'island of Atlas') is a fictional island mentioned in Plato's works Timaeus and Critias as part of an allegory on the hubris of nations. In the story, Atlantis is described as a naval empire that had conquered Europe as far as central Italy, and the African coast as far as Egypt, making it the literary counter-image of the Achaemenid Empire. After an ill-fated attempt to conquer "Ancient Athens", Atlantis falls out of favor with the deities and submerges into the Atlantic Ocean.
https://en.wikipedia.org/wiki/Atlantis