  The theory of structure formation predicts that galaxies form within extended
massive dark matter halos built from smaller pieces that collided and merged,
resulting in the hierarchy of galaxies, groups, and clusters observed today.
Here we present constrained numerical simulations designed to match the
observed local universe as well as possible and to study the formation,
evolution and present day properties of such dark matter halos in different
environments. Simulations have been done with different versions of the
Adaptive Refinement Tree (ART) N-body code, some of them including eulerian
gasdynamics.
