  We investigate, in the framework of (2+1) dimensional gravity, stationary,
rotationally symmetric gravitational sources of the perfect fluid type,
embedded in a space of arbitrary cosmological constant. We show that the
matching conditions between the interior and exterior geometries imply
restrictions on the physical parameters of the solutions. In particular,
imposing finite sources and absence of closed timelike curves privileges
negative values of the cosmological constant, yielding exterior vacuum
geometries of rotating black hole type. In the special case of static sources,
we prove the complete integrability of the field equations and show that the
sources' masses are bounded from above and, for vanishing cosmological
constant, generally equal to one. We also discuss and illustrate the stationary
configurations by explicitly solving the field equations for constant
mass--energy densities. If the pressure vanishes, we recover as interior
geometries Godel like metrics defined on causally well behaved domains, but
with unphysical values of the mass to angular momentum ratio. The introduction
of pressure in the sources cures the latter problem and leads to physically
more relevant models.

General Relativity and Quantum Cosmology