The CARLA survey is the largest survey of z>1.3 clusters and protoclusters. In this talk I will introduce the survey and present some of the most recent and interesting results. Our large Spitzer programme targeted 420 very powerful, high redshift radio-loud AGN (RLAGN) for a total of more than 400 hours, discovering 200 (proto)clusters at redshifts z=1.3-3. Using these data I will show that dense, gas-rich environments likely trigger the formation of a radio-jet, explaining why distant, powerful RLAGN are commonly located within forming galaxy clusters, and that RLAGN trace mature, passively evolving clusters as well as young collapsing protoclusters. Twelve CARLA clusters/protoclusters have already been spectroscopically confirmed and I will describe the ongoing effort to confirm 20 more with MOSFIRE and HST grism observations.
Finally, I will show how this survey has transformed our understanding of cluster galaxy formation at high redshift. I will present our latest results showing the evolution of the galaxy luminosity function and galaxy colours of clusters at redshifts greater than 1.5. Our results are consistent with passive evolution models and high formation redshifts, and we show that cluster galaxies must have formed over a 1-3 Gyr epoch.