  We determine loop space decompositions of simply-connected four-manifolds,
$(n-1)$-connected $2n$-dimensional manifolds provided $n\notin\{4,8\}$, and
connected sums of products of two spheres. These are obtained as special cases
of a more general loop space decomposition of certain torsion-free
$CW$-complexes with well-behaved skeleta and some Poincar\'{e} duality
features.
