Hello Rodger
The Fairfax Seminary Hospital was in Alexandria, Virginia. It is currently called the Virginia Theological Seminary.
See:
http://www.vts.edu
http://www.mikelynaugh.com/VirtualCivilWar/New/Originals2/pages/FairfaxSeminaryAlexandria.html
http://www.edinborough.com/Books/HospitalDays.html