The history of the IMU can be traced back to 1920, with traces going back to the time before World War I. After World War II, the IMU was reestablished, and has been growing steadily since then. Up to recently, the “IMU Archive” was located with the IMU Secretary of the time, and thus was moving whenever a new Secretary was elected. In addition, there were archives located in Zurich and Helsinki. With the decision to create a permanent IMU Secretariat in Berlin from 2011, all archival material has been moved to Berlin. It is the plan to digitize all stored material, and make it freely available, in accordance with relevant regulations. As of now, the proceedings of all international congresses since 1897 are freely available.