Atlantis (Ancient Greek: Ἀτλαντὶς νῆσος, "island of Atlas") is a fictional island first mentioned in Plato's dialogues Timaeus and Critias, written in c. 360 BC. In Plato's story, Atlantis represents the antagonist naval power that, despite ruling many parts of Western Europe and Northern Africa, suffered a crushing defeat at the hands of “Ancient Athens”, the pseudo-historic embodiment of the Plato's ideal state (see The Republic). The tale, one of many such stories in Plato's work, serves as an allegory for a nation's fate due to hubris.
In these dialogues, Critias claims that an island called Atlantis was swallowed by the sea about 9,200 years previously. This story was passed down to him through his grandfather, Dropides, who in turn got it from Solon, the famous Athenian lawmaker who got the story from an Egyptian sanctuary. Plato's dialogues locate the island in the Atlantic Pelagos "Atlantic Sea", "in front of" the Pillars of Hercules (Ηράκλειες Στήλες) and facing a district called modern Gades or Gadira (Gadiron), a location that some modern Atlantis researchers associate with modern Gibraltar; however various locations have been proposed.
Despite its minor importance in Plato's work, the Atlantis story had a considerable impact on literature ever since classical antiquity. Plato's vague indications on the time of the events and the supposed location of Atlantis—"beyond the Pillars of Hercules"—became a gateway for pseudoscientific speculation. As a theme, Atlantis inspires today's light fiction, from science fiction to comic books to films. Its name has become a byword for any and all supposed advanced prehistoric lost civilizations.
 Location hypotheses of Atlantis
The legendary island of Atlantis has many proposed real-world settings:
- North-West of Egypt: From Greece to Spain: Thera (Santorini), near Cyprus, Helike, Sardinia, Sicily, Malta
- North-East of Egypt: From Middle East to the Black Sea: Middle East, Turkey, Troy, Black Sea
- Around Gibraltar: Near to the Pillars of Hercules: Andalusia, Spartel Bank, Morocco
- Atlantic Ocean (West): Azores Islands, Canary Islands, Madeira and Cape Verde, Northern Spain
- Atlantic Ocean (North): Irish Sea, Great Britain, Ireland, North Sea, Denmark, Finland, Sweden
- Americas: South America, Cuba
- Other locations: Antarctica, Indonesia/Sundaland, North Pole