Tucked away 35 steps up the spiral staircase is a collection in a 13th century space with medieval floor tiles and coloured armorial glass.
The collection of books and manuscripts were the gift of Frances Seymour of Drayton Bassett, who gave her late husband’s library to the cathedral in 1674 after his death.
The size of the original bequest is not clear, but there are more than 400 books and manuscripts at the cathedral.
Visitors can see behind the scenes of the library and view some of the treasures it stores on dedicated tours, being offered on eight Wednesdays and Saturdays throughout the year.
Clare Townsend, Cathedral librarian, said: "This is a great opportunity to see some of our most treasured books and manuscripts from the cathedral library.
"This year we are showcasing items from the library of William Seymour, 2nd Duke of Somerset, gifted by his widow Frances in 1673, including our illuminated copy of Chaucer’s Canterbury Tales.
"There will also be two accessible tours on Wednesday 18 May and Wednesday 14 September at 10.30am designed for those unable to ascend the spiral staircase."
Accessible tours will take place at ground level in the Chapter House.
The tour will last around 90 minutes with tickets costing £18 available at lichfield-cathedral.org/tours.