The Karl Christ Prize is dedicated to the memory of the Marburg ancient historian Karl Christ (1923-2008). Since 2013, the prize has been awarded for outstanding scientific achievements in the field of ancient history and related disciplines as well as in the history of science and reception in antiquity. The fifth prizewinner is Klaus Hallof. The brilliant epigraphist has dedicated his entire research life to the Greek inscription work of the Berlin Academy, the Inscriptiones Graecae. Even under the difficult conditions in the GDR, with great inner independence he carried out basic research in the field of classical studies and opened up sources without which new insights into ancient history could not be achieved. As an excellent scientist and successful scientific organizer, he transformed the Greek inscription work into a showcase project of the classical studies activities of the Berlin Academy. Again and again he dealt with the history of his subject and thus continued Karl Christ's research into the history of science. The lecture that Klaus Hallof gave at the ceremony on April 2, 2022 was dedicated to the topic: "Kos 243 v. Chr. Chr. Ein Europäische Projekt" and is published here together with Stefan Rebenich's eulogy for the award winner.