On the special occasion of the 125th anniversary in 2012 of the PTB and its predecessor PTR, this second edition is presented (in CD) with a new chapter on the current impact of quantum standards.In 1887, the Physikalisch-Technische Bundesanstalt (PTB) was originally founded as the Physikalisch-Technische Reichsanstalt (PTR) in Berlin in order to promote basic research in physics. It subsequently developed into the largest research center worldwide as a place where scientists could concentrate exclusively on their research subject, and served as a model for similar institutes established in other countries.Within a very short time, the PTR produced extremely important scientific results that cemented its international position at the top, such as Max Planck’s radiation law and energy quantization theory as well as Walther Meissner’s discovery of the Meissner effect which represented a turning point in the field of superconductivity. This book describes the scientific and industrial milieu of the time, and explains in detail the role of the key people, including Albert Einstein’s involvement with the PTR. A brief discussion on how the PTR was affected by the Nazi dictatorship in Germany is also given.