Nuclear discs in external galaxies and the Milky Way: building "bulges" without mergers

In this talk I will present two recent papers of the TIMER project with MUSE at the VLT. We have obtained high signal-to-noise and spatial resolution integral-field spectroscopy data of the inner few kpc of 21 nearby massive barred galaxies, allowing studies of the stellar kinematics and population properties with unprecedented spatial resolution. We establish the presence of nuclear discs in 19 galaxies and show that their kinematics and stellar populations are consistent with the bar-driven secular evolution picture for their formation. We also show that such nuclear discs are recovered as exponential, photometric "bulges" in careful, state-of-the-art image decompositions. Furthermore, we propose a scenario whereby such nuclear discs form from star formation in successively larger nuclear rings built by the bar. Finally, I put these observations in the context of recent results concerning the central region of our own Milky Way