I never noticed this former US airfield despite so many departures out of FRA. It is just south of Darmstadt where the A5 and A67 intersect (visible in the background). The DC-8 that was displayed at the FRA observation deck for so many years is now kept at this airfield, along with some other historic aviation exhibits.
Overview of the "August-Euler-Flugplatz", since 2005 in possession of the "Technische Universität Darmstadt" [Canon EOS 50D + Canon EF 24-105mm L IS USM]