Secret Tunnels Under the USA?

I've always liked the idea of secret underground cities for some reason. I imagine all the reasonable people live down there and they leave all the nuts on the surface. Dennis Balthaser has an interesting article up on the UFO Chronicles about government secrecy containing a link to one of the biggest tunnel boring machines I've seen yet:




I wonder if this is nuclear powered like some of our submarines. I've heard they can melt rock and that they leave behind tunnel walls that are like melted glass. Another rumor I've found interesting is that there are many secret tunnels all across the USA with high speed magnetic levitation bullet trains running through them.  Fun idea. Of course, there could be various dark sides to the whole thing. One is simply that we are wasting money on these black projects:

Dennis writes:

... During WWII, Sweden had an elaborate Naval facility build into the side of a mountain, with water access, known as the Musko Naval Base, consisting not only of dry docks for ships and submarines, but the whole base was built into the side and under the mountain. It contained repair factories, a hospital with a thousand beds, dining rooms and barracks.

My civil engineering background was aroused when I started researching underground facilities, and I quickly learned that the equipment and personnel required to build some of these elaborate underground complexes is readily available. Several types of tunnel boring equipment sometimes referred to as TBM’s have been manufactured by companies like Bechtel, the Robbins Company, and Dawn Engineering, as well as several foreign equipment manufacturers. They vary greatly in size and can be of the “gouging” type, flame cutters and nuclear, the latter being developed at Los Alamos National Laboratory in New Mexico with a United States Patent Office date of September 26, 1972

Many other facilities are known to exist, and you have the assurance of our government that with the use of our tax dollars, our government and military leaders are at least protected even if we are not, and in most cases their purpose, cost and location will be denied, or attempted to remain in secrecy. ... - ufoc

I've read much darker scenarios, such as reptilian and little gray aliens working alongside the humans in these underground facilities. I've also heard the disturbing idea that the thousands of people who go missing each year are being abducted by "aliens" working with our secret government, and that they are transported below to be used for breeding experiments, or as slaves, or ... food. A creepy thought, that would make a great horror movie.

There are also rumors on the "pro-noia" side: The shadow government, while getting a bad rap on the blogosphere, has actually saved life on Earth several times. They have for years been using secret superior technology to avert nuclear wars and environmental disasters. Theirs is a thankless job and they are the  source of many of our best UFO sightings. Rather than taking slaves or eating people they occasionally find worthy individuals on the surface who are asked to join them.

Then you have the theory that both of the above are true and that there have been great underground wars which continue to this day.