[SunkenCiv]

AA Photo

[Eddie01]

Look, I’m not saying it was aliens but...

[JoeFromSidney]

I took a tour of one of those underground cities when I was teaching in Turkey. They are carved into thick layers of solidified volcanic ash. The builders carved benches and tables in the rooms, so furniture wasn't needed. Niches in the walls, for lamps, still had soot above them from the lamps. Absolutely amazing.

What was really amazing was the ventilation system, which brought fresh air into the city and allowed it to flow through the city before being exhausted.

[Elsiejay]

One would conclude that the presence of such huge works of excavation would be clearly indicated by huge deposits of “spoil,” the excavated soil and rock material that had to have been transported and deposited at some place not too far distant.