Grasping the nature of spacetime is still an ongoing and controversial enterprise. The content of this volume, dedicated to the 100th anniversary of the publication of General Relativity, is a step aimed at furthering it. All papers present some theoretical novelties concerning conceptual, physical and mathematical aspects of spacetime, the embedding of it into a quantum picture of reality for the elucidation of the nature of gravity and of other basic physical effects, and the role of the notion of spacetime in other research fields. This volume will be of interest to researchers both on spacetime physics and on its philosophical analysis, as well as to students and those who would like to learn about the discussed problems of this important branch of modern physics.