In the winter of 1979-1980 I was at Hahn Air Base in West Germany. A TDY to a base in far northern Germany was offered to a bunch of us flightline grunts but I hated the cold and heard it was much worse up there. When the guys came back a couple weeks later they told a story of going by invitation to the "other side" of this German air base, going down a ladder or metal winding stair (as I recall) where a few lights were turned on revealing a cavern with at least a couple of FW-190's. They couldn't go close or take pictures. I know - I should have made good notes about the base name and all other details at the time, but I'm afraid I was negligent. Really regret it today because the witnesses were quite sincere and had no motives and were not thetype to fabricate the story.
I posted something about this on TOCH message board a few years ago and some other posters seemed to know about it. Can't find that posting now.
http://forum.12oclockhigh.net