Nanometer-sized grains may self-organize into macro-domains in a polycrystal undergoing a structural phase transition. Formation of such macro-domains is a very efficient strain-relieving mechanism, as demonstrated here. The Figure shows a tethered self-supported BaTiO3 film viewed with cross-polarized light, illustrating a large in-plane anisotropy due to the self-organization of ferroelectric grains in curved regions.