  Several arguments suggest that quasars at z > 4 may be in the cores of future
giant ellipticals, and forming at the very highest peaks of the primordial
density field. A strong bias-driven primordial clustering is then expected in
these fields, which are naturally interpreted as the cores of future rich
clusters. High-redshift quasars can thus be used as markers of some of the
earliest galaxy formation sites. Recent discoveries of (proto)galaxy companions
of z > 4 quasars, and hints of strong clustering among high-z quasars give some
support to this idea. The frequency of companions is much higher than is
expected for a general field, or the upper limits for comparable redshifts in
the HDF. Clustering of quasars themselves at z > 3 or 4 may reflect the
primordial large-scale structure.
