The two fundamental pillars of physics for over 100 years have been quantum theory and general relativity, but their unification at short distances remains elusive, both technically and conceptually. This work is a philosophical investigation of the second kind of problem, and in particular of the striking fact that in many approaches to 'quantum gravity' classical spacetime structures are not merely quantized, but arguably absent—so that spacetime is not merely a classical limit, but 'emergent'. This issue is not only central to the problem of quantum gravity, but of deep significance for our philosophical understanding of physical reality, promising a conceptual revolution at least as profound as Einstein's. Nick Huggett and Christian Wüthrich explore the question of spacetime emergence, for philosophers of metaphysics and science, and argue for spacetime functionalism as the answer to seeing how something non-spatiotemporal could ever appear as space and time. More technical