Recent research in elementary particle physics is concentrating a great amount of effort on neutrino oscillation experiments. These studies require the accurate pointing of neutrino beams between two distant points. The Fermi National Accelerator Laboratory (Fermilab) intends to build a new particle beamline to direct a beam of muon neutrinos from its Main Injector toward a far-off (735 km away) underground detector capable of searching for non-zero neutrino mass by looking for neutrino oscillations. This paper describes the GPS work carried out to accurately position the reference ground marks at the two sites from which the spatial orientation of the baseline can be accurately determined. The effect of plate rotations on the absolute orientation of the baseline was also investigated.