Navigation on the PDC portal meets a dual need for access to the digitised collections. On the one hand, the non-specialist user can browse the collection through the different sections, the structure of which is related to outstanding and representative elements of the collection (format, subject matter, period). On the other hand, PDC users who require a specialized search have this option available.

The basic organization of the works contained in PDC is structured around collections by type of format:

• Manuscripts
• Incunablula
• Early printed works
• Engravings and drawings
• Maps and plans
• Photographs
• Historical doctoral theses (up to 1920)

The large collections of Manuscripts, Incunabula and Printed Works can also be accessed by periods, and if we access the thematic collections we will find a set of collections selected by subject, origin or other criteria, which facilitate a more user-friendly navigation.