The exploration of the outer halo of the Milky Way through wide-sky photometric and spectroscopic surveys has confirmed that the outer layers of our Galaxy are the result of the continuos merging of protogalactic fragments, as predicted by the cosmological Lambda-Cold Dark Matter simulations. Since the arrival of the European Space Agency Mission Gaia, we have had a unique opportunity to disenable the stellar populations found along a single line of sight, thanks to the precious information gathered for more than one billion objects. In this talk, I will present some of our ongoing projects based on Gaia data aiming to take different facets of the Galactic Archaeology field of research, including the search for hypervelocity stars, the detection of stellar haloes surrounding Galactic globular clusters, and the discovery of new halo substructures.