Gaia has revolutionized our knowledge about the Milky way and its close environment by calculating precise orbits for the stars of the disk as well as those of the globular clusters and dwarf galaxies populating its halo. This allowed us to establish the first rotation curve of the Milky Way, as well as the first relationship that characterizes its history of accretion of smaller galaxies, over 13 billion years. We infer a fairly small mass for the Galaxy, which can be compared to cosmological expectations. I will also compared it to the recent mass estimate of our large neighbor, the Andromeda galaxy, on the basis of its rotation curve.
