A multisymplectic structure on a manifold is defined by a closed differenti
al form with zero characteristic distribution. Starting from the linear cas
e, some of the basic properties of multisymplectic structures are described
. Various examples of multisymplectic manifolds are considered, and special
attention is paid to the canonical multisymplectic structure living on a b
undle of exterior k-forms on a manifold. For a class of multisymplectic man
ifolds admitting a 'Lagrangian' fibration, a general structure theorem is g
iven which, in particular, leads to a classification of these manifolds in
terms of a prescribed family of cohomology classes.