  We present the results of a wide-field survey for extremely red objects (EROs
hereafter), the widest so far, based on Ks and R band imaging. The survey
covers 701 arcmin^2 and it is 85% complete to Ks\leq18.8 over the whole area
and to Ks\leq19.2 over 447.5 arcmin^2. Thanks to the wide field covered, a
complete sample of about 400 EROs with R-Ks\geq5 was selected. The distribution
of the EROs on the sky is strongly inhomogeneous, being characterized by
overdensities and large voids. We detect at the 8 sigma level a strong
clustering signal of the EROs which is about an order of magnitude larger than
the clustering of K-selected field galaxies in the same magnitude range. A
smooth trend of increasing clustering amplitude with the R-Ks color is
observed. These results are strong evidence that the largest fraction of EROs
is composed of high-z ellipticals, of which we detect for the first time the
z\simgt1 large scale structure clustering signal. We show how the surface
density variations of the ERO population found in our survey can explain the
highly discrepant results obtained so far on the density of z > 1 ellipticals,
and we briefly discuss the main implications of our results for the evolution
of elliptical galaxies. The number counts and the colors of the K-selected
field galaxies are also presented and briefly discussed.
