Oslo Public Library is the municipal public library serving Oslo, Norway and is the country's first and largest library. It employs over 300 people and has over 20 branches throughout the city. Registered users may use the library every day, even when it is not staffed, from 7am to 11pm. It is also possible to borrow and return books when the library is not staffed. One of the most prized books in the library's collection is the Vulgate bible of Aslak Bolt (1430–1450), Norway's only preserved liturgical handwritten manuscript from medieval times.