We Americans often earlier church interiors to have been bare, unadorned wood or stone. That's part of our Puritain heritage, and also partly fed by the fact that medieval cathedrals today are usually bare stone. But the medieval church would have been brightly colored - polychromed - and the walls were often decorated with elaborate paintings of religious scenes. The Painted Church website (an older site full of useful material) collects, by topic, images of most of the extant wall paintings in medieval England.
The most famous Anglo-Saxon bling may be the Sutton Hoo Ship Burial treasures, but the largest hoard of Anglo-Saxon goldwork is the Staffordshire Hoard. Discovered in 2009 in western England, the Staffordshire Hoard is a jaw-dropping, eye-dazzling collection of intricately crafted works of armorial art.
. . . but the details behind da Vinci's Mona Lisa have long been obscure. Now, archaeologists in Italy have opened the grave believed to house the bones of Lisa Gherardini, the woman believed to have been the model for the famous painting. You can read about the excavation, Lisa's life, and the archaeological team's goals at Discovery News, as well as an update on the project.