Using the UltraVISTA catalogs, I present the evolution since z=3 of the properties of the progenitors of today’s ultra-massive galaxies (i.e., Mstar=6x10^11 Msun; UMGs). At z < 1, the progenitors constitute a homogeneous population of only quiescent galaxies with old stellar populations. At z > 1, the contribution from star-forming galaxies progressively increases, with the progenitors at 2.5 < z < 3 being dominated by massive (Mstar~2x10^11 Msun), dusty (Av~1-2.2 mag), star-forming (SFR~100-400 Msun/yr) galaxies. Recent findings on the environment of the progenitors are presented, along with the separate role of in-situ star formation and merging in the growth of the stellar content as a function of cosmic time. Combined with recent results from a spectroscopic campaign targeting ultra-massive galaxies at 3 < z < 4 selected from the NEWFIRM Medium-Band Survey, a revised evolutionary path for the formation of local UMGs over the last 12 Gyr is present. I will conclude presenting recent results from the combination of UltraVISTA and 3D-HST data on the evolution of the fractions of quiescent, unobscured and dusty star-forming galaxies as a function of stellar mass since z=3, and introducing on-going multi-wavelength surveys and upcoming data releases.