For Black Mesa-esque military bases: where the hell do people get their information?

Pardon me if I come across as a bit ignorant since I’m not actually a designer, but I was reading this thread on the Black Mesa Source forums, and I was baffled at the sheer wealth of information the OP has about how all of what’s there fits together.

Where in the hell do designers get their information on how an archetypal military research facility is laid out, how its individual facilities are laid out, how they are run, and how they’re connected to each other? Are there books on this stuff?

EDIT: Wrong link, fixed.

Well, there are a lot of old military bases that are either open to the public, or are very well documented. You gotta remember that Black Mesa is implied to have been originally built during the Cold War as a military facility.

Then again, we’ve known for ages that, stacked together, the maps from Half-Life 1 and 2 don’t make any sense at all. Office space is right above a rocket testing silo, an anti-matter spectrometer is a wall away from a train tunnel filled with radioactive goo, a coastal highway goes into a 180º curve to get on a bridge that leads to nowhere, etc.