The internal evolution of disk galaxies like the Milky Way is driven by non-axisymmetries (bars) and the implied angular momentum transfer of the matter; baryons are essentially driven inwards to build a more concentrated disk. This mass concentration may lead to the decoupling of a secondary bar, since the orbit precessing frequency is then much enhanced. Vertical resonances with the bar will form a box/peanut bulge on a Gyr time-scale. Gas flows due to gravity torques can lead to a young nuclear disk forming stars, revealed by a σ-drop in velocity dispersion. These gas flows moderated by feedback produce intermittent accretion onto the super-massive black hole, and cycles of AGN activity. The fountain effect due to nuclear star formation may lead to inclined, and even polar nuclear disks.