When is Atlantis alleged to have disappeared?

Question

When is Atlantis alleged to have disappeared?

Answer 1

Atlantis (in Greek, Ἀτλαντὶς νῆσος, "island of Atlas") is the name of a legendary island first mentioned in Plato's dialogues Timaeus and Critias.

In Plato's account, Atlantis, lying "beyond the Pillars of Hercules", was a naval power that conquered many parts of Western Europe and Africa 9,000 years before the time of Solon, or approximately 9500 BC. After a failed attempt to invade Athens, Atlantis sank into the ocean "in a single day and night of misfortune".

As a story embedded in Plato's dialogues, Atlantis is generally seen as a myth created by Plato to illustrate his political theories. Although the function of the story of Atlantis seems clear to most scholars, they dispute whether and how much Plato's account was inspired by older traditions. 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.

Atlantis was finally alleged to have disappeared in the 15th century

Answer 2

1200 B.C.

Answer 3

1600 B.C.

Answer 4

Not real.  So the answer is "Never".