Ancient Alien Tunnels, new human tunnels?

I have heard stories about ancient alien tunnels (USA, Brazil) crisscrossing the planet between their underground bases, I have also heard about secret military tunnels under the USA and other countries. Do these tunnels actually exist or are they the fanciful dreams of people with too much time on their hands? What kind of technology would be needed to build them in order to outlast earthquakes and time. Please enlighten.

It would be extremely difficult to make tunnels that far apart because they would have to be extremely deep to go undetected.

The material the tunnels are lined/constructed with would have to be super strong. The earth moves constantly, and at that depth, alot is going on. It would be extremely hard for it to take an earthquake or somehting of the sort.

Highly unlikely unless some kind of alien or secret technology is used.
But what would the use for such a network of tunnels?
The united states wouldnt bother doing something so expensive if it only lead to places within the united states, unless it was between military bases in the unites states. like Area 51 connected to a base somewhere in montana or something.

There are tunnels being used....with vehicles that can use them as astronomical speeds..... the elite who actively use them, do not know who created them...however I do know that one entrance point is at Montauk Point, being the home of the Montauk Project..... They used to take many victims of mind-control and genetic experimentation to Montauk using the tunnels...

Kind Regards
Merger