  Recent observations have revealed the structural properties of the dark and
luminous mass distribution in spirals. These results led to the vision of a new
and amazing scenario. The investigation of single and coadded objects has shown
that the rotation curves of spirals follow, from their centers out to their
virial radii, an universal profile that implies a tuned combination of their
stellar disk and dark halo mass distributions. This, alongside with accurate
mass modeling of individual galaxies, poses important challenges to the
presently theoretically favored $\Lambda$CDM Cosmology.
