Star formation and supermassive black hole growth were most active at cosmic noon (z~2). Massive galaxies appear to experience accelerated growth at early cosmic times, and eventually quench their star formation and become more bulge-dominated. Exactly why these transformations take place is unclear. Mergers and active galactic nuclei feedback are often invoked as explanations, but a consensus is yet to be reached. I will discuss how multiwavelength observations of stellar populations and multiphase gas of distant galaxies can shed new light on the complex problem of galaxy evolution.