Do you believe in lost ancient civilizations?

For example, do you believe that there was a lost city of Atlantis, a lost continent called Mu, or any fabled tales about lost places and civilizations? Is so, how accurate do you think modern-day depictions are of these places?

----

I find Atlantis to be somewhat intriguing, because the Richat Structure in Mauritania matches up with some of the details described by the Greek philosopher Plato, except that the place is a desert rather than a sunken island. There is, however, a theory that a flood event occurred from an asteroid impact 12,000 years ago (which also seems to be inspirations of flood event stories for the Bible and the Epic of Gilgamesh), so maybe it is possible that there was an Atlantis that was an island years ago and then the water receded over millennia.

The lost continent of Mu is kind of interesting though, because it's supposed to be a more massive landmass. I would imagine that if it existed, it would probably be submerged (like the ancient continent Zealandia). There is some pseudoarchaeological claims that the Yonaguni Monument is the remnant of Mu though, so I find that kind of interesting.