This area of our research is concerned with addressing the following unresolved puzzles of the Standard Model: The origin of mass (the origin of the weak scale, its stability under radiative corrections, and the solution to the hierarchy problem); The problem of flavour (the problem of the undetermined fermion masses and mixing angles (including neutrino masses and mixing angles); The question of unification (the question of whether the three known forces of the standard model may be related into a grand unified theory, and whether such a theory could also include a unification with gravity). The approaches we develop are based on Supersymmetric Grand Unified Theories (SUSY GUTs) with extra Family Symmetries or String-Inspired models involving D-branes embedded in Extra Dimensions. We are interested in the experimental consequences of these theories at experiments such as the forthcoming Large Hadron Collider or the many Neutrino Experiments.