  The goal of the Pierre Auger Observatory is to determine the still unknown
nature and origin of ultra-high energy cosmic rays. The study of these elusive
particles probes astrophysical sites of particle acceleration as well as
fundamental interactions at energies unattainable in accelerator facilities.
Auger combines two observational techniques, a large surface array and air
fluorescence detectors, to observe the extended air showers generated in the
atmosphere by cosmic rays. This hybrid observation yields an excellent
resolution and allows for important cross-checks. The Auger South site, located
in Mendoza (Argentina), is now nearing completion, with 60% of its surface
array and three out of its four fluorescence detectors in operation. First
results on the energy spectrum measurement, the search for anisotropies in
arrival directions and the upper limit on the photon fraction are discussed.
