Propulsion Park (Building 4205's Rocket Engine Display) Rendering
Outside the front entrance of Marshall Space Flight Center Building 4205 is a rocket engine display which I understand is informally called "Propulsion Park". On my first visit to Propulsion Park, it sported F-1, linear aerospike, and NERVA engines. In November 2013, a Shuttle Solid Rocket Booster joined these other engines.
This display appears to have been a long time in the making. During a visit to MSFC in October 2008, I found that the F-1 engine was staged behind Building 4205 (although I did not at the time know it was destined for display in front of 4250). The F-1 was installed in October 2009.
But planning for Propulsion Park started even before then. I have an undated rendering of Propulsion Park, below. (The graphics file had a modification date of October 2, 2007, so it would seem to have to be at least that old.)
This rendering shows not only the F-1, linear aerospike (which, if you look closely, is actually firing!), NERVA, and SRB which are present today, but also show a J-2 and a Space Shuttle Main Engine.
I don't know if this was just an early concept which subsequently pared back or whether Propulsion Park has an expansion in the works, but I do know that on my September 2013 visit I saw that they had already created signs for the J-2 and SSME.