  We review the present observational knowledge on the spatial distribution and
the physical state of the different (molecular, atomic and ionized) components
of the interstellar gas in the innermost 3 kpc of our Galaxy -- a region which
we refer to as the interstellar Galactic bulge, to distinguish it from its
stellar counterpart. We try to interpret the observations in the framework of
recent dynamical models of interstellar gas flows in the gravitational
potential of a barred galaxy. Finally, relying on both the relevant
observations and their theoretical interpretation, we propose a model for the
space-averaged density of each component of the interstellar gas in the
interstellar Galactic bulge.
