  The Sagittarius dwarf spheroidal (Sgr) and a few paculiar Galactic Globular
Clusters (GGC) can be considered as building blocks of theGalactic Halo. We
present a series of results based on a wide field photometry of the Sgr system
and the GGC M22. In particular for Sgr we present: (1) the detection of the
RGB-bump, a feature that together with the shape of the RGB can be used to
constrain the allowed range of age and metallicity and (2) the detection of a
clear blue horizontal branch which probes the existance of a metal poor
population. In the case of M22 we present clear evidence that differential
reddening is the primary cause for the observed spread of the evolutionary
sequences.
