  We construct conformastat spherically symmetric spacetimes representing
anisotropic fluid matter distributions from given solutions of the Poisson's
equation of Newtonian gravity and its corresponding circular speed profile. As
simple examples, we present three families of spherically symmetric spacetimes
which we apply in constructing new models of relativistic anisotropic thick
spherical shells, and of relativistic galaxy models composite by a central
spherical bulge, the thick disk and the dark matter halo, writing in this case
the metric in cylindrical coordinates. Moreover, the geodesic motion of test
particles in stable circular orbits around such structures is studied. We build
anisotropic fluid sources for these spacetimes which satisfy all the energy
conditions and the principal stresses are positive quantities (pressure).
