The notion that high-mass young stars are only observable when on the ZAMS was quite standard in the 80's. Francesco started to investigate if this was really the case using IRAS data, and triggered a fertile systematic observational campaign from the NIR to the radio that showed that indeed an evolutionary sequence for young massive YSOs could be observed. The Herschel infrared Galactic Plane survey represents the ideal end-point of Francesco's original thread.