Kola Superdeep Borehole
I have mentioned this before, but as a reminder via Wiki:
The Kola Superdeep Borehole is the result of a scientific drilling project of the Soviet Union on the Kola Peninsula. The project attempted to drill as deep as possible into the Earth's crust. Drilling began on 24 May 1970 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig. A number of boreholes were drilled by branching from a central hole. The deepest, SG-3, reached 12,262 metres (40,230 ft) (2.21 leagues) in 1989, and is the deepest hole ever drilled, and the deepest artificial point on Earth.So what happened?
Well I leave you with two images.
One, the place looks like it was destroyed (click for larger view):
Yeah, many old USSR sites look bad. The collapse and all that. I get it.
But then why was the borehole WELDED SHUT and left INTACT all this time? (click for larger view):
Have a good night.