Atlantis

Atlantis is a legendary island first mentioned in Plato's dialogues Timaeus and Critias, written about 360 BC. According to Plato, Atlantis was a naval power lying "in front of the Pillars of Hercules" that conquered many parts of Western Europe and Africa in approximately 9600 BC. After a failed attempt to invade Athens, Atlantis sank into the ocean "in a single day and night of misfortune".

Scholars dispute whether and how much Plato's story or account was inspired by older traditions. Plato claims that his accounts stem from a visit to Egypt by the legendary Athenian lawgiver Solon in the 6th century BC. In Egypt, Solon met a priest of Sais, who translated the history of ancient Athens and Atlantis, recorded on papyri in Egyptian hieroglyphs, into Greek. Some scholars argue Plato drew upon memories of past events such as the Thera eruption or the Trojan War, while others insist that he took inspiration from contemporary events like the destruction of Helike in 373 BC or the failed Athenian invasion of Sicily in 415–413 BC.

Description of Atlantis
In one of the earliest recorded accounts of Atlantis, The island was larger than Ancient Libya and Asia Minor combined, but it was sunk by an earthquake and became an impassable mud shoal, inhibiting travel to any part of the ocean. The Egyptians described Atlantis as an island comprising mostly mountains in the northern portions and along the shore, and encompassing a great plain of an oblong shape in the south "extending in one direction three thousand stadia [about 555 km; 345 mi], but across the center inland it was two thousand stadia [about 370 km; 230 mi]." Fifty stadia [9 km; 6 mi] from the coast was a mountain that was low on all sides...broke it off all round about... the central island itself was five stades in diameter [about 0.92 km; 0.57 mi].

Mythological Beginnings
Poseidon carved the mountain where his love dwelt into a palace and enclosed it with three circular moats of increasing width, varying from one to three stadia and separated by rings of land proportional in size. The Atlanteans then built bridges northward from the mountain, making a route to the rest of the island. They dug a great canal to the sea, and alongside the bridges carved tunnels into the rings of rock so that ships could pass into the city around the mountain; they carved docks from the rock walls of the moats. Every passage to the city was guarded by gates and towers, and a wall surrounded each of the city's rings. The walls were constructed of red, white and black rocks quarried from the moats, and were covered with brass, tin and the precious metal orichalcum.

The esoteric text Oera Linda, published in 1872, mentions it under the name Atland. The book claims that it was submerged in 2193 BC, the same year that 19th century almanacs, following traditional Biblical chronology, gave for Noah's flood.

Theosophists believe the civilization of Atlantis reached its peak between 1,000,000 and 900,000 years ago but destroyed itself through internal warfare brought about by the inhabitants' dangerous use of magical powers.