For the selection of works presented in this series, the concept of treasure is not limited to the rarest and most precious books and collections of BGUC, but also those that “speak eloquently of things that at each moment and in each context are valued: ultimately, the quality of treasure is not in the object itself but in the eyes of those who see and show it", maintains A. E. Maia do Amaral. The “BGUC Treasures” sessions are organized by the League of Friends of the General Library of the University of Coimbra (LIBUC). Works such as the «Crónica de Nuremberga», the «Bíblia Atlântica», the 1st edition of «Os Lusíadas», the typescript of «Praça da Canção» by Manuel Alegre and recently, on May 10th, the story of the discovery of the letter from the Jesuit astronomer Cristóvão Borri to Dom André de Almada. The engraving of the Moon seen by Cristóvão Borri, on July 18, 1627, with a telescope belonging to Dom André Vaz de Almada, is most likely the oldest graphic document of an astronomical observation made in Portugal.