In my talk I will review our understanding, through cosmological simulations, of the evolution of galaxy clusters from redshift z~2-3, to the recent cosmic epoch. Through a comparison with observational data at different wavelengths I will assess the capability of simulations to trace the fast evolution of such cosmic structures from their proto-cluster stage, characterized by a strongly star forming galaxy population embedded in a dynamically disturbed inter-galactic medium, to their relaxed stage at low redshift, characterized by a passive galaxy population immersed in a relatively relaxed intra-cluster medium. In this context, I will highlight successes of simulations, and critically assess their limitations and what we should learn from them.