Atlantis is a continent whose destruction and technology is a thing of widespread myth and speculation. Therefore, there are many different examples and possibilities when dealing with something that happened so very long ago.
Atlantis was destroyed by astrodial impact on, what in modern times what we know as, All Hollows Eve (Halloween). The remnants of this once great place is now the caribbean islands. The rest of the remains lie on the floor of the Atlantic ocean.
Atlantians had what seems advanced technology. Utilizing crystals and an innate spiritual connection to the powers that be. The option to use this great power could only lead down two paths. That of ascension, That of destruction. In the journey of discovery, the majority of the people became over thrown by selfishness and greed, leading them to attract to themselves a reality in which they destroyed themselves.
Where Was Atlantis?
Islands of Altantis
This island is just opposite Unal. The largest or greatest city on Undal is Keor. This is the place where the Priesthood of Atlantis was. The other side of the island of Undal was called Chien. Chien was where the philosophers and scientists were. The whole island was surrounded by terraced walls and divided across the center, between Keor and Chien. No one was allowed on either side of the island except for a pass. Jelani Mu-Stafa Solamen was a God from Keor. He was the only God allowed to migrate without utilization of a pass. 
- The Emerald Tablets of Thoth-The-Atlantean (ISBN 0966531205)