Oxford University’s Bodleian Library has put its archives online. The Library’s Introduction page notes:
“The Bodleian Library is one of the oldest libraries in Europe, and in Britain is second in size only to the British Library. Together, the Bodleian Libraries hold over 13 million printed items. First opened to scholars in 1602, it incorporates an earlier library built by the University in the 15th century to house books donated by Humfrey, Duke of Gloucester. Since 1602 it has expanded, slowly at first but with increasing momentum over the last 150 years, to keep pace with the ever-growing accumulation of books, papers and other materials, but the core of the old buildings has remained intact.
Have a look around!