The University Library in Belgrade opened its doors to its users on May 24, 1926. The University of Belgrade has its own library, which has always been a support to the academic community. This year, on the Day of Cyril and Methodius, the University Library „Svetozar Marković“ in Belgrade will mark a century of successful work. Through a brief historical development, we will show their mutual connection. As a sign of gratitude, in the hall of the University Library, above the Carnegie bust, there is an inscription: „It is known that this Book Depository came into being and was founded as the fruit of a noble thought and a noble gift from the Carnegie Endowment, and that by the will of God it was opened on May 24, 1926.“