This collection of lectures and essays by eminent researchers in the field, many of them nobel laureates, is an outgrow of a special event held at CERN in late 2009, coinciding with the start of LHC operations. Careful transcriptions of the lectures have been worked out, subsequently validated and edited by the lecturers themselves. This unique insight into the history of the field includes also some perspectives on modern developments and will benefit everyone working in the field, as well as historians of science.
