  We present a simulation of twelve globular clusters with different
concentration, distance, and background population, whose properties are
transformed into Gaia observables with the help of the lates Gaia science
performances prescriptions. We adopt simplified crowding receipts, based on
five years of simulations performed by DPAC (Data Processing and Analysis
Consortium) scientists, to explore the effect of crowding and to give a basic
idea of what will be made possible by Gaia in the field of Galactic globular
clusters observations.
