  Over the last 30 years or so, a handful of events observed in ground-based
cosmic ray detectors seem to have opened a new window in the field of
high-energy astrophysics. These events have energies exceeding 5x10**19 eV (the
region of the so-called Greisen-Zatsepin-Kuzmin spectral cutoff); they seem to
come from no known astrophysical source; their chemical composition is mostly
unknown; no conventional accelerating mechanism is considered as being able to
explain their production and propagation to earth. Only a dedicated detector
can bring in the high-quality and statistically significant data needed to
solve this long-lasting puzzle: this is the aim of the Auger Observatory
project around which a world-wide collaboration is being mobilized.
