Metal-poor stars play a key role in understanding the nucleosynthesis of heavy elements in the early Universe, as their chemical abundances reflect the composition of the gas in which they formed. High-resolution spectroscopic studies show that very metal-poor stars exhibit a wide spread in the abundances of neutron-capture elements. This large star-to-star scatter seems to suggest that that multiple astrophysical sites contributed to their production, operating under different physical conditions. The nucleosynthesis processes and formation sites responsible for the production of neutron-capture elements in the early Galaxy are still a matter of debate, as several processes could be involved (e.g. s- process, r- process, i-process, weak r-process, weak s-process, ...). To trace the formation and evolution of heavy elements in the Milky Way we need detailed chemical abundances for a large sample of metal-poor ([Fe/H]<-1) stars, in order to compare them with the predictions of theoretical models. In this talk, I will present recent results from two projects, CERES and MINCE, which aim to characterise the nucleosynthesis and Galactic chemical evolution of heavy elements, and future work within the OUTLIERS project in IAC.