[Out of the Box]

Originally Posted by EireEngineer

Well, for one where is it?

I don't know. Some suggest we look at the bottom of the Atlantic ocean, others suggest we look beneath the ice of Antarctica. There are numerous different theories that haven't sufficiently been tested yet.

Originally Posted by EireEngineer

We have a fairly advanced civilization. Look at all of the technology and material that we would leave behind if we vanished suddenly. I am fairly certain the Aluminum shell of the laptop I am typeing on would survive damn near anything, even though the guts of it would be pretty useless in a 1000 years.

Many sources place the end of the lost advanced civilisation at the end of the last ice age or about 12500 years ago. Many materials could have been reused by later cultures or disappeared due to corrosion. If the culture in question really submerged, it's also possible a lot of technology is now at the bottom of the ocean. We're left with speculation since we can only guess what materials this civilisation used (assuming such a civilisation existed in the first place).