  We present multi-wavelength observations of the northern population of Omega
Cen from the main-sequence turn-off to high on the red giant branch. We show
that the best information about the metallicity and age of the stars can be
gained from combining vby, B-I and V-I colors (in the absence of spectroscopy).
We confirm our results for the main-sequence turn-off stars: there is at least
a
  3 Gyr age spread. We use proper motion studies to confirm cluster membership
at and above the level of the horizontal branch, and we show that the age
spread is maintained amongst stars from the subgiant branch through the red
giants. The available evidence suggests that Omega Cen is the core of a
disrupted dwarf galaxy.
