This paper explores conditions
under which a metric space S satisfies the following Disjoint Disks Property: any two
maps of the standard 2-cell B2 into S can be approximated by maps having
disjoint images. Among its many applications, it provides a proof that if Y is
the cell-like image of an n-manifold (n ≥ 3), then Y × E2 has the Disjoint
Disks Property, which implies that Y × E2 is a manifold. It adds further
evidence for the unifying force of this property by giving comparatively easy
proofs for established facts about certain decomposition spaces that are
manifolds.