Oxford University and the Vatican are joining forces to make ancient texts available for free online.
The project will see 1.5 million pages from the collections of the Bodleian Libraries and the Biblioteca Apostolica Vaticana digitised over the next four years.
The works are from three areas - Greek manuscripts, 15th century printed books, and Hebrew manuscripts and early printed books.
Sarah Thomas, Bodley's librarian, said: "Transforming these ancient texts and images into digital form helps transcend the limitations of time and space which have in the past restricted access to knowledge.
"Scholars will be able to interrogate these documents in fresh approaches as a result of their online availability. Today's world, and tomorrow's, is one of global connectedness.
"The Bodleian Libraries are pleased to have the opportunity to work closely with Biblioteca Apostolica Vaticana in this cross-cultural collaboration."
About two-thirds of the works will come from the Vatican, with the remainder from the Bodleian. The subject areas were chosen "for the strength of the collections in both libraries and their importance for scholarship in their respective fields", a University of Oxford spokeswoman said.
Lord Patten of Barnes, chancellor of the university, said: "By making these collections available online we give the wider public access to a small but significant part of the world's heritage."
The project has been funded by a £2 million grant from the Polonsky Foundation.
Monsignor Cesare Pasini, prefect of the Vatican Library, said: "With this joint initiative, the two libraries continue to accomplish their mission for the benefit of science and culture; it represents a great step forward in the Vatican Library's entry into the digital age, and the library is particularly grateful to Dr Leonard Polonsky for giving us this extraordinary impetus."