The detection of GW170817 was a watershed moment in astrophysics, providing the first direct glimpse of a neutron-star merger through both gravitational waves and electromagnetic radiation. This event confirmed that such mergers forge much of the Universe’s heaviest elements, including gold and platinum, and offered unprecedented opportunities to probe fundamental physics—from general relativity to nuclear astrophysics. Many questions remain, however, from the detailed mechanisms of r-process nucleosynthesis to the full diversity of transient phenomena. In this talk, I highlight recent advances in understanding the origin of the heaviest elements and show how multi-messenger observations are reshaping our view of transient astrophysical events.