Based on a new large, homogeneous photometric database of 69 Galactic globular clusters extended out to 42 kpc from the galactic center, a set of distance and reddening free relative age indicators has been measured: delta (V-I)@2.5 and Delta VHBTO. Using this two independent indicators and two recent updated libraries of isochrones we have found that self-consistent relative ages can be estimated for our GGCs sample. The main results are: (a) most clusters and all with [Fe/h]<-1.2 are old and coeval; (b) there is no trend of the age with the Galactocentric distance out to 25 kpc from the galactic center; (c) there is a mild indication (but still based on a limited number of clusters) that clusters beyond 25kpc are slightly younger (d) there is no age-metallicity trend and (e) for more metal-rich clusters ([Fe/h]>-1.2) there are indication of a larger age dispersion, of the order of 10-15%. From these results, a tentative interpretation of the Milky Way formation can be given. First, the GC formation process started at the same zero age throughout the halo including the outer regions, out to the current ˜ 42 kpc. The so-called disk globulars were formed at a later time (˜ 15% lower age). Finally, significantly younger halo GGCs are found at any distance out to RGC˜ 30 kpc. For these, a possible scenario associated with mergers of dwarf galaxies to the Milky Way is suggested.