Establishing an evolutionary sequence for high-mass young stellar objects (YSOs) is one of the hot topics of current star formation. Differently to the low-mass star formation case, high-mass stars reach the zero-age main sequence while they still undergo heavy accretion, and their powerful radiation pressure should halt the infall of material, thus inhibiting growth of the stellar mass beyond 8 Msun. Recent theories, however, propose that high accretion rates and/or accretion through massive disks could overcome this problem, and explain the formation of stars with masses up to 140 Msun. In this talk I will characterize, from an observational point of view, an evolutionary scheme for the massive star formation process: which starts with dense cores with almost no (star-formation) activity, and ends with the development of HII regions that disrupt their natal cloud. I will present recent results on the physical properties of dense cores, molecular outflows, circumstellar disks, and HII regions obtained with a number of different instruments, including the Atacama Large Millimeter Array.