This paper reviews the vicissitudes experienced by the library of the Reial Acadèmia de Bones Lletres de Barcelona since its inception in the eighteenth century to the present. As it has been generally stated, the collections of the library and archive constitute a basis for studying the activities of this institution and the cultural, artistic and literary milieu of the eighteenth century; but beyond that, the library holds some medieval manuscripts preserved thanks to the efforts undertaken by some scholars and members of the academy to safeguard the books from the confiscation of church properties after the exclaustration and the burning of convents during the years 1835-1836. Therefore, one of the main goals of this paper is to focus on these medieval witnesses, their codicological analysis and literary content, and finally to trace their conventual origin, a process that has been possible in part thanks to the testimony of father Jaime Villanueva and his Viage literario a las iglesias de España (1803-1854).