Having always thought the Spacex Base Plan had just been made up by a studio artist, I was amazed to hear from Tony Panther that it's actually very much based on reality. As Tony discovered, the layout is a pretty realistic representation of a 1960s NASA launch complex at Cape Canaveral!
Much as Tony showed it to me, a satellite view of such a launch complex reveals what the Base Plan represents, albeit in a simple, abstract graphic treatment. But the features marked on the Base Plan (launch pad, block house, storage locations, etc) do match with the real thing (except the two circles).
These particular launch pads are part of "Missile Row" on Cape Canaveral. The satellite view above shows Launch Complex 14, which is closest to the layout of the Spacex Base Plan and for which I found the best images. The one below gives a good view of the installations, just before the launch of Mercury-Atlas 9 sitting on Pad 14. Called Faith 7, the Mercury capsule would take astronaut Gordon Cooper on the fourth US orbital mission on 15 May 1963.
A fun fact: if you scroll down the Google satellite image, you'll see that the next launch complex to the south is now being used by the SpaceX company to test landing rockets!