>>767877This is the entrance to the 900 Level as of last year, about a 10 minute hike up the mountain from the mill site. NCGC have since moved the concrete blocks back into the entrance to prevent 4x4 vehicles from entering.
There are videos on YouTube of people driving jeeps inside of the 900 Level:
https://www.youtube.com/watch?v=9TZvNirvIXw