Luciana Bianchi, from the Johns Hopkins University, will hold the next SISSA colloquium on June 24, 2014, at 12.00 am, room 128. Studies of young stellar populations in local galaxies, spanning a variety of environments and physical conditions, reveal the modalities of the star-formation process and the co-evolution of massive stars and dust. Massive stars drive the dynamical and chemical evolution of their host galaxy. Mapped across large portions of galaxies, they provide a precise time and space tomography of the young stellar populations, because of their fast evolutionary time-scales, revealing how gas and dust condense to form stars, and how local star-bursts evolve and dissolve with time.