Flying back from Mexico a couple of years ago I was recording video out the window, bored with the long flight. What I taped was a 'fake-looking' mountain covered in what looks like mesh. I have asked a few people that should know what it is and nobody would explain it. One person I talked to was a friend of a friend who had worked at NORAD. He looked at me after I told him, kind of chuckled nervously and said, "I wish I could tell you," as if he knew what it was but could not tell me.
My guess is that it is several miles long comparing it to the mine. If you look closely, you can see that it has ribs under the mesh covering to give us a guess on the height, and also that it is a hollow structure.
Google Earth provides a street view of the highway going in from the south to within a few miles. I also looked up the exact spot using the same program and they show only images of before the mountain. The time line of satellite photos shows inconsistencies of trying to hide something.
The mountain borders an old mining site.
The coordinates are 32' 42' 04.72" N, 110' 40' 36.39" W. It's just to the west of Mamoth, north-northeast of Tuscon.