  In the recent times a lot of effort has been devoted to improve our knowledge
about the space of string theory vacua (``the landscape'') to find statistical
grounds to justify how and why the theory selects its vacuum. Particularly
interesting are those vacua that preserve some supersymmetry, which are always
supersymmetric solutions of some supergravity theory. After an general
introduction to how the pursuit of unification has lead to the vacuum selection
problem, we are going to review some recent results on the problem of finding
all the supersymmetric solutions of a supergravity theory applied to the
N=4,d=4 supergravity case.
