We present V,I deep CCD photometry for three fields of the dwarf galaxy in Sagittarius (Sgr), located at l=5.6{deg}, b=-14.1{deg}. One of the fields is centered on the globular cluster NGC 6715 (M54), which lies in one of the dense clumps of the Sgr galaxy. Comparing the CMD of Sgr with those of globular clusters which are believed to be kinematically associated with the dwarf galaxy (Da Costa & Armandroff, 1995AJ....109.2533D), we conclude that the stellar population of Sgr presents a spread in metallicity of -0.71<=[Fe/H]<=-1.58, and that the dominant population (=~10Gyr old) is extremely similar to the star content of the associated globular cluster Terzan 7. The estimated distance to Sgr is d=~24.55Kpc.