How is spacetime built? What is it built from? What can asking these questions tell us about the nature of black holes, the beginnings of our universe, or the nature of quantum gravity? After a brief review of the nature and use of dualities in modern string theory and quantum gravity, we explore three approaches to theoretically constructing spacetime itself: entanglement entropy, quasinormal modes, and the "double copy" prescription. We discuss how these approaches provide new theoretical and physical windows into the nature of spacetime.