actually, there probably IS such a place as black mesa.. in UTAH, or Texas somewhere. Allthose cowboy films you see withthe big mushroom shaped rocks in the bacground. they're mesa. .
OTOH "black Mesa" as in the nice high tech research facility probably doesnt exist.
the same way that Area 51 doesn't exist.
and white sands is just a propulsion lab.
and the british C&C bunker is just "underground tunnels".
and the white hall nuclear bunker is just used for storage.
whatever provides positive bouyancy for your aquious transport vehicle