Twenty-seven printers' marks decorate Blegen Library.  These devices originated as early trademarks which were used by printers to identify their work.  The fourth floor window grills on the outside of the building show among several devices the mark of Peter Schoeffer, whose double shield emblem used in his Psalter of 1457 is the earliest known printer's mark.  Adorning the inner entrance doors are 15^th century devices which used the combination of the cross, the orb and the merchant's mark of 4.  In the lobby is perhaps the most famous printer's mark, the emblem of Aldus Manutius of Venice.  Its familiar dolphin and anchor are set in bronze above the drinking fountain at the side of the grand staircase.

Other beautiful printers' marks on the fourth floor are executed in delicate plasterwork on walls and above portals.  Additional case bronze devices are placed in the doors on the sixth floor.