"This volume pays tribute to the career and scientific accomplishments of Walter Alvarez with papers related to the many topics he has covered: tectonics of microplates, structural geology, paleomagnetics, Apennine sedimentary sequences, geoarchaeology and Roman volcanics, Big History, and the discovery of evidence for a large asteroidal impact event at the Cretaceous-Tertiary (now Cretaceous-Paleogene) boundary site in Gubbio, Italy"--