  We present results from two high-resolution hydrodynamical simulations of
proto-cluster regions at z~2.1. The simulations have been compared to
observational results for the socalled Spiderweb galaxy system, the core of a
putative proto-cluster region at z = 2.16, found around a radio galaxy. The
simulated regions have been chosen so as to form a poor cluster with M200~10^14
h-1 Msun (C1) and a rich cluster with M200~2x10^15 h-1 Msun (C2) at z = 0. The
simulated proto-clusters show evidence of ongoing assembly of a dominating
central galaxy. The stellar mass of the brightest cluster galaxy (BCG) of the
C2 system is in excess with respect to observational estimates for the
Spiderweb galaxy, with a total star formation rate which is also larger than
indicated by observations. We find that the projected velocities of galaxies in
the C2 cluster are consistent with observations, while those measured for the
poorer cluster C1 are too low compared to the observed velocities. We argue
that the Spiderweb complex resemble the high-redshift progenitor of a rich
galaxy cluster. Our results indicate that the included supernovae feedback is
not enough to suppress star formation in these systems, supporting the need of
introducing AGN feedback. According to our simulations, a diffuse atmosphere of
hot gas in hydrostatic equilibrium should already be present at this redshift,
and enriched at a level comparable to that of nearby galaxy clusters. The
presence of this gas should be detectable with future deep X-ray observations.
