I really think that there is something underground!
For such a high security base like a51 it is logical that they have at least
some underground labs, bunkers, storages and a server-room or supercomputer
room.
Maybe not the size, we would expect at dulce or pine gap.
A additional reason could be the radiation from the nuclear-tests at yucca-flat.
They are only really secured under the ground.
This is an endless discussion like the S-4 installation until we have the ultimate proof.
Here are some links which could be underground entrance at A51:
local.google.com...,-115.823734&spn=0.002725,0.00434
local.google.com...,-115.842912&spn=0.003081,0.005423&t=k&om=1
Is this maybe an entrance, build into mountain and try to hide from satellites, between the white house and the white dot in the middle?
An entrance like the one on S-4?