Brady Haran visits the RAS Library and Archives and asks to look at the oldest book in our collection. This video on the Objectivity YouTube channel features De natura rerum by Isidore of Seville. This text about nature and astronomy was originally written by Isidore in the 7th century CE. The version held in in the RAS library was printed in 1472.
Books printed in Europe in the earliest stages of printing, before 1501, are known as incunables. Another very early printed book is The Sphere by John of Holywood.
For the full series of videos on the Objectivity YouTube channel featuring treasures from the RAS Library and Archives, see this playlist.