one place that will come readily to mind might be "The Skunk Works" a.k.a. Area 51 ~ Groom Lake
Groom Lake and Area 51 were never "The Skunk Works". That was originally at the Lockheed Burbank plant, where such aircraft as the P-38, SR-71, and F-117 were developed and built.
But by the late-1980's that area was shifting to residential and commercial, so it was moved to Plant 42 in Palmdale. There the B-1, B-2. and F-35 were developed and built.
Groom Lake is simply a test area where those aircraft and others that are of a "black" nature are tested. As opposed to at Edwards Air Force Base where public tests are conducted.
It helps if you first know what you are talking about.