"The Fitzwilliam Museum is the art museum of the University of Cambridge (UK). It was founded in 1816 by the bequest of the VIIth Viscount Fitzwilliam of Merrion and contains magnificient collections of works of art and antiquities of national and international importance." Contains quite of number of medieval manuscripts and other art items.

"The Jorvik Viking Centre in York, England, has now been open over 15 years and seen 11 million visitors travel back in time to the Viking Age."

A very excellent introduction to life in medieval London. The site includes lot of images, themes, games, timeline and more. Will require Flash in places. "Journey across more than a thousand years – from Anglo-Saxon settlement in the 5th century, through Viking raids and the Norman Conquest of 1066, to the splendour and bustle of England’s 16th-century capital, and the dramatic results of Henry VIII's Dissolution of the Monasteries."

Though not exclusively medieval in nature, the Pierpoint Morgan Library is has some very wonderful medieval texts in it's collection. There are some examples of a few of those texts available on it's web site. Be sure to check out a new exhibit called A Medieval Year.

"The Web Gallery of Art is a virtual museum and searchable database of European painting and sculpture of the Gothic, Renaissance and Baroque periods (1200-1700), currently containing over 6,500 reproductions. Biographies, commentaries, guided tours are available. Free postcard service is provided for the visitors."