Jake daniel
I agree, unless there was some apocalyptic event. then they built the underground city to avoid the heat. There is a good example of this in the remote south Australian desert today, an entire town lives underground.
J'mal Sanchez
Those who don't know their true past are doomed to repeat it. People are asleep to true life including our true past. Very soon people are going to start making the connection that we lived our past, that we build these tunnels and everything we see today. You have lived as every species in your evolutionary line to be where you are now. You have been born and died right here on earth as all the different animals that the evidence says we evolved from. The truth is stranger than fiction but it is the real truth that will set you free. Google
Truth Contest and read the top entry called "The Present". This is truth the evidence says is true.