  High resolution synthetic stellar libraries are of fundamental importance for
the preparation of the Gaia Mission. We present new sets of spectral stellar
libraries covering two spectral ranges: 300 --1100 nm at 0.1 nm resolution, and
840 -- 890 nm at 0.001 nm resolution. These libraries span a large range in
atmospheric parameters, from super-metal-rich to very metal-poor (-5.0
$<$[Fe/H]$<$+1.0), from cool to hot (\teff=3000--50000 K) stars, including
peculiar abundance variations. The spectral resolution, spectral type coverage
and number of models represent a substantial improvement over previous
libraries used in population synthesis models and in atmospheric analysis.
