away from our Galaxy, is the part of the Universe that can be best observed and thus is able to provide the greatest constraining power on cosmological theories.

Using the Constrained Simulations (CS) technique, I will first show how the main properties of the largest structures that surround us can be reconstructed in N-body simulations. Then, I will discuss some applications on the small scales, where the dynamics of the local group of Galaxies can be linked to its cosmological environment.

This effectively provides us a numerical laboratory to test structure formation, allowing a direct comparison between simulated objects and observations while also providing precise and testable predictions.

The techniques and the results presented in this talk are based on the latest publications from the CLUES collaboration, http://arxiv.org/abs/1510.04900[1] and http://arxiv.org/abs/1602.03919[2]