For more than a 100 hundred years globular clusters have been studied with the promise to understand better the formation and evolution of galaxies, and to this date we keep learning from their teachings. In this talk I will present my collaborators and my work on globular clusters at the different distances and for different purposes: from the globular cluster systems of distant isolated elliptical galaxies, to the study of bulge Galactic clusters to shed light on the IMF of metal-rich stellar populations, to finally the study of individual stars in nearby clusters to understand the mass limit of self-enrichment.