No real evidence of aliens visiting this planet or our solar system exists therfore it is not known.
It was easier to build above ground, instead of under.
because there was a forest under it
They live underground.
It is easier to build on top of the ground because you would have to dig a giant hole in the ground and build from what you dug, making more work than what was needed.
under ground chambers
long houses some in lakes and humans some lived under ground
Under ground to everywhere in the house plumbing ( everywhere )
auctally she didn'd build it she just led it
under ground chambers
under ground chambers
no, only in dark places, and under rocks and houses and sheds etc.
they made cliff house in stead of living in pit houses under ground