  High redshift (z >~ 1) clusters are ideal probes to study the formation and
evolution of large scale structures and galaxies in the universe. A 10-m class
ground based telescope, X-ray observatories (Chandra, XMM-Newton) and HST/ACS
are allowing us to perform an unprecedented study of distant massive clusters
of galaxies in the redshift range 0.84<z<1.3, selected from X-rays surveys. In
this paper we summarize our results on the structure and dynamics of two of
these clusters derived from imaging and spectroscopic data as well as our
results on the evolution of early-type galaxies.
