Did Atlantis Exist?

Yes Atlantis did exist, they were

Inga Rumpf: lead vocal, acoustic guitar, percussion
Adrian M. Askew: keyboards, vocals
Alex Conti: guitars, vocals
Karl-Heinz Schott: bass
Ringo Funk: drums, percussion

Atlantis was not only the name of the legendary island, the famous Greek author Plato mentioned, but also the name of a band formed by ex-Frumpy musicians Inga Rumpf, Jean-Jacques Kravetz and Karl-Heinz Schott, in late Summer, 1972. The initial line-up included guitarist Frank Dietz and ex-Emergency drummer Curt Cress (later with Triumvirat, Passport).

The band played a few live gigs in Germany before they recorded their debut in London's Island Studios. The US magazine, Cash Box, compared Atlantis with the Doobie Brothers and praised Inga Rumpf's blues-tinged voice. Shortly before the group went on a four week tour of England with Procol Harum, Traffic, Vinegar Joe and the Sharks, Cress and Dietz left and were temporarily supplanted by Udo Lindenberg and George Meier. After the tour, Atlantis recruited Dieter Bornschlegel (ex-Traumtorte) on guitar and Ringo Funk (ex-Jeronimo) on drums as new permanent members.

...... and so on

So where was it?

Google Earth says it's in Florida.
They may be suffering from delusions of grandeur.
(there's a lot of it about)

According to Dr. Elizabeth Weir The Lost City of Atlantis Has Been Found! It is located well past Uranus and is hidden deep within the Pegasus galaxy.