  The recent Gaia Third Data Release contains a homogeneous analysis of
millions of high-quality Radial Velocity Spectrometer (RVS) stellar spectra by
the GSP-Spec module. This led to the estimation of millions of individual
chemical abundances and allows us to chemically map the Milky Way. Among the
published GSP-Spec abundances, three heavy-elements produced by
neutron-captures in stellar interiors can be found: Ce, Zr and Nd. We use a
sample of about 30,000 LTE Ce abundances, selected after applying different
combinations of GSP-Spec flags. Thanks to the Gaia DR3 astrometric data and
radial velocities, we explore the cerium content in the Milky Way and, in
particular, in its halo and disc components. The high quality of the Ce
GSP-Spec abundances is quantified thanks to literature comparisons. We found a
rather flat [Ce/Fe] versus [M/H] trend. We also found a flat radial gradient in
the disc derived from field stars and, independently, from about 50 open
clusters, in agreement with previous studies. The [Ce/Fe] vertical gradient has
also been estimated. We also report an increasing [Ce/Ca] vs [Ca/H] in the
disc, illustrating the late contribution of AGB with respect to SN II. Our
cerium abundances in the disc, including the young massive population, are well
reproduced by a new three-infall chemical evolution model. Among the halo
population, the M 4 globular cluster is found to be enriched in cerium.
Moreover, eleven stars with cerium abundances belonging to the Thamnos, Helmi
Stream and Gaia-Sausage-Enceladus accreted systems were identified from
chemo-dynamical diagnostics. We found that the Helmi Stream could be slightly
underabundant in cerium, compared to the two other systems. This work
illustrates the high quality of the GSP-Spec chemical abundances, that
significantly contributes to unveil the heavy elements evolution history of the
Milky Way.
