How should we understand a body's place in the physical universe? Must it be explained in terms of its relation to a region of space? Or can it be accounted for in some other way? Such questions are of primary import within contemporary metaphysics and the philosophy of science. In attempting to answer these questions, scholars in these fields have routinely turned to the views of earlier thinkers.In Aquinas's Ontology of Place, Jeffrey Brower explores the theory of place as developed by Thomas Aquinas (1225-1274), arguably the most influential thinker of the Middle Ages. In Brower's account, the key to understanding Aquinas's theory is to be found in two underexplored aspects of his natural philosophy. First, in his account of local motion (i.e., locomotion or change of place); and second, in his account of magnitude (i.e., extension or extended objects). Beginning with a novel analysis of both accounts, which primarily arise from Aquinas's well-known commentary on Aristotle's Physics, Brower systematically examines the respective elements of Aquinas's theory, documenting their implications about the places of bodies in general and the place of 'the heavens'. The resulting picture not only sheds new light on Aquinas's ontology of the material world but also provides a wholesale alternative to standard contemporary theories of place.