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We present a new determination of the metallicity distribution, age, andluminosity function of the Galactic bulge stellar population. By combiningnear-IR data from the 2MASS survey, from the SOFI imager at ESO NTT and theNICMOS camera on board HST we were able to construct color-magnitude diagrams(CMD) and luminosity functions (LF) with large statistics and small photometricerrors from the Asymptotic Giant Branch (AGB) and Red Giant Branch (RGB) tipdown to $\sim 0.15 M_\odot$. This is the most extended and complete LF so farobtained for the galactic bulge. Similar near-IR data for a disk control fieldwere used to decontaminate the bulge CMDs from foreground disk stars, and henceto set stronger constraint on the bulge age, which we found to be as large asthat of Galactic globular clusters, or $\gsim 10$ Gyr. No trace is found forany younger stellar population. Synthetic CMDs have been constructed tosimulate the effect of photometric errors, blending, differential reddening,metallicity dispersion and depth effect in the comparison with theobservational data. By combining the near-IR data with optical ones, from theWide Field Imager at the ESO/MPG 2.2m telescope, a disk-decontaminated$(M_K,V-K)$ CMD has been constructed and used to derive the bulge metallicitydistribution, by comparison with empirical RGB templates. The bulge metallicityis found to peak at near solar value, with a sharp cutoff just above solar, anda tail towards lower metallicity that does not appreciably extend below[M/H]$\sim-1.5$.

Age and metallicity distribution of the Galactic bulge from extensive optical and near-IR stellar photometry