After reading through Mystic Odysseys of Theros, I excavated and old project. Creating a setting for the Atlantean world. When I start something new part of the process is to outline my thoughts to give me a direction. This is that document.
Atlantis working document
Plato tells us that the Atlantis he is talking about existed some 9000 years before he tells the story. If I start from there, then Atlantis existed at the end of the last ice age. (it's at this point you should look up "Last Glacial maximum") As Atlantis was supposed to be a society more advanced than than the Egyptians or Ancient Greeks, that means the denizens of Atlantis had to have evolved before us standard average humans. The Atlantians, The First ones, Proto-Sapiens. Living in a rather savage and untamed world, they would have been more hardy and robust than normal humans. Atlantians are stronger, taller, heal faster, and live longer naturally. They would have been living in a world shaped by them long before the lesser sapiens gathered together in hunting groups for safety.
We have now established the premise upon which we shall flesh out the legend.
The Island: Placed somewhere beyond the Pillars of Hercules in the Atlantic ocean. We could take Plato's description literally, but this for fantasy, so we can take a few liberties with some of the details. Applying a small fraction of logic, mixed with a gratuitous amount of pop culture and historical speculation we will put Atlantis in place that gives us a reasonable explanation as to how an entire island could be swallowed by the sea. This location is right on top of intersection of 3 tectonic plates. Go look at the Azores in Google maps, switch to satellite view and look around the ocean floor around there. If Atlantis is going be anywhere, I would put it there.
The North American Plate, Eurasian Plate, and the African Plate form an island. This island is not meant to last, the island formed on top of a massive magma chamber. The island is naturally warmed by the geothermal properties of sitting on a few billion tons of molten rock. The island would have an abundance of life that would take advantage of the utopia like conditions. We now have an island approximately the size of half of Australia. Sitting just outside the Pillars of Hercules, just like Plato said.
The World: Atlantis existed (according to legend) some 12,000 - 15,000 years ago. That is a very long time. Very very long. The world would be unrecognizable from what it looks like today. Sea levels would be drastically lower. Many of the straights and natural channels would be high and dry. Most of the water being still frozen as ice age glaciers.
First, the catastrophe that wiped out Atlantis (in my version) happens when the magma chamber collapses and the cavity swallows Atlantis whole. If we are to blame the Earth's crust for the destruction of Atlantis, why not throw a few more major incidents to liven things up. The tectonic plate boundary between the Eurasian and African plates, runs the length of Mediterranean. So, when Atlantis gets swallowed, we can reasonably assume that the tectonic plates would have to adjust. That adjustment is what caused the library at Alexandria to slide into the sea, it caused the volcano at Santorini to blow, and take out most of the Minoan civilization. It caused the boot of Italy to go from a platform heel down to the stiletto spike it is today. The adjustment finished off the Atlantean civilization. The Sahara desert would have still been green grassland. Glacial ice would still be covering much of north america and northern europe. 12,000 years ago, smilodons (saber tooth tigers), woolly mammoths, and dodo birds would still be around. There are some monsters bases to work from there. The British isles would have been the British island (it sits right next to a major fault line too)
The cities of the Atlantean empire: If we go by Plato's description of Atlantis, there are the Rings of Poseidon surrounding the Temple of Poseidon. Go do an image search for the City of Carthage. Carthage was supposed to have a circular dock, very reminiscent of the Rings of Poseidon. The walls were said to be formidable, built up defenses that took many years to complete. I'm thinking it started as an Atlantean colony. Minoa might have been another colony. The Atlanteans would have put cities where it made the most sense to support their trading and conquests. Istanbul (was Constantinople) would have been a colony. From what I've learned of the city of Troy, it could be a colony.
