  A geometric formulation which describes extended supergravities in any
dimension in presence of electric and magnetic sources is presented. In this
framework the underlying duality symmetries of the theories are manifest.
Particular emphasis is given to the construction of central and matter charges
and to the symplectic structure of all D=4, N-extended theories. The latter may
be traced back to the existence, for N>2, of a flat symplectic bundle which is
the N>2 generalization of N=2 Special Geometry.
