Many are hidden in remote monasteries or temples whose walls are crumbling, but a remarkable project has recorded the paintings before they disappear for ever.
Inspiration and ideas for the students' work came from small sketchbooks in which they recorded drawings, paintings and written ideas to explore in finished work.
The earliest recorded artworks – paintings on the cave walls of Lascaux in southern France – are from the palaeolithic era, about 20,000 years ago.
"If we are going to find this hidden history, the answers will be there - in the archives, records, paintings and stories of these great houses," Willis-Brown says.
A 13th-century English artist named Matthew Paris is represented by large close-up portraits of the Madonna and Child and two images of the adult Jesus that probably record paintings he saw.
The apartment is filled with her "addictions," as she calls her collections of handmade books, zines, records, paintings, drawings, Outsider art and objects like a crocheted anatomical heart by Merrilee Challiss, an Alabama artist, and a hand-stitched stuffed yellow lion she bought for $50 at a store called ReForm School in Los Angeles.
Filled with serious books, classical records, paintings and drawings and etchings, artifacts and sculptures and objets d'art, the interiors give Zuckerman the idea that possessions can be "bound up with pleasurable living and, at the same time, with morality, with mankind's aspiration to achieve significance through connoisseurship and thought".
Mr Morrison has to keep an eye on the 277 medieval manuscripts, 45 books from the infancy of printing between 1450 and 1500, archive documents including written records, paintings and photographs and a collection of music books.
Whereas in past times woman were oftentimes accorded minimal acclaim comparative to their male counterparts who may have accomplished similar or even later feats, today woman are increasingly being given their due as many of these early explorations and accomplishments were preserved via extensive written records, paintings and photographs of journeys.
The art historian Birgit Schwarz, author of a study of Hitler's collection for his museum in Linz, discovered in Washington a photograph album that apparently records the paintings in Hitler's private Munich apartment.
