In this important volume, major events and personalities of 20th century physics are portrayed through recollections and historiographical works of one of the most prominent figures of European science. A former student of Enrico Fermi, and a leading personality of physical research and science policy in postwar Italy, Edoardo Amaldi devoted part of his career to documenting, both as witness and as historian, some significant moments of 20th century science. The focus of the book is on the European scene, ranging from nuclear research in Rome in the 1930s to particle physics at CERN, and includes biographies of physicists such as Ettore Majorana, Bruno Touschek and Fritz Houtermans.Edoardo Amaldi (Carpaneto, 1908 - Roma, 1989) was one of the leading figures in twentieth century Italian science. He was conferred his degree in physics at Rome University in 1929 and played an active role (as a member of the team of young physicists known as ?the boys of via Panisperna?) in the fundamental research on artificial induced radioactivity and the properties of neutrons, which won the group's leader Enrico Fermi the Nobel Prize for physics in 1938. Following Fermi's departure for the United States in 1938 and the disruption of the original group, Amaldi took upon himself the task of reorganising the research in physics in the difficult situation of post-war Italy. His own research went from nuclear physics to cosmic ray physics, elementary particles and, in later years, gravitational waves. Active research was for him always coupled to a direct involvement as a statesman of science and an organiser: he was the leading figure in the establishment of INFN (National Institute for Nuclear Physics) and has played a major role, as spokesman of the Italian scientific community, in the creation of CERN, the large European laboratory for high energy physics. He also actively supported the formation of a similar trans-national joint venture in space science, which gave birth to the European Space Agency. In these and several other scientific organisations, he was often entrusted with directive responsibilities. In his later years, he developed a keen interest in the history of his discipline. This gave rise to a rich production of historiographic material, of which a significant sample is collected in this volume.