Gloucester Cathedral will allow guests to explore its hidden 15th century library on Saturday 22 April.
Visitors will have the opportunity to go on a cathedral library tour, giving them access to areas usually closed off from the public.
The monastic library is hidden away at the top of a spiral staircase and is home to books and manuscripts that date back to the 11th century.
Guests will have access to rarely-viewed items including the first edition of Sir Robert Atkyn's history of Gloucestershire and antique maps of the country by the famous mapmaker John Speed, published in 1611.
The tours will take place on Saturday 22 April and a few other dates throughout the year.