  We compute all loop topological string amplitudes on orientifolds of local
Calabi-Yau manifolds, by using geometric transitions involving SO/Sp
Chern-Simons theory, localization on the moduli space of holomorphic maps with
involution, and the topological vertex. In particular we count Klein bottles
and projective planes with any number of handles in some Calabi-Yau
orientifolds.
