I think a lot of folks missed this part.....
Mark Allen M wrote:
This would NOT include underwater, wrecks in jungles, parts & pieces scattered about.
While it's intriguing to imagine secret tunnels full of forgotten aircraft, I think your picture was telling. The caption mentions "tunnels under the city are quite extensive and hardly touched since they were vacated after the war," but the picture appears to show someone giving a guided tour. Doing a Google image search turns up many similar images of guided tours of "secret Nazi tunnels" in Germany and elsewhere in Europe. Are there still tunnels and bunkers somewhere in Europe that remain undiscovered? I find it hard to believe that 75 years after the end of the war anything would still be hidden. It seems possible, but unlikely. Notable exception in the fiction world; Clive Cussler's intrepid hero Dirk Pitt found a hidden squadron of Me-262's in Japan (I think) in his novel
Dragon.I think it's more likely that ones and twos may crop up here and there, particularly as their original owners pass on, as someone further up the thread pointed out. Who knows what could be hidden in the back of a barn/warehouse/hangar in the out-of-the-way corners of the US and the world.
I'd assume a disassembled and crated-up aircraft would be more likely to have remained undiscovered, as opposed to a fully assembled aircraft. A P-51 would take a couple of big crates, but again, the US is full of big warehouses and other industrial buildings, to say nothing of what may be in other countries.
Interesting to daydream about....