 Complete the following phrase:  Church frescos or church wall paintings Danish: kalkmalerier are to be found in some 600 churches across Denmark, no doubt representing the highest concentration of surviving church murals anywhere in the world. Most of them date back to the Middle Ages and were uncovered by Jacob Kornerup 18251913 who carried out restoration work in 80 churches across the country towards the end of the 19th century. They lay hidden for centuries as after the reformation, they were covered with limewash Danish: kalk only to be revealed and restored during the course of the 19th and 20th centuries. In most of Europe medieval frescos, extremely common in the Middle Ages, were more likely to be removed completely during the Reformation or in subsequent rebuildings, or merely as they aged. The oldest frescos, dating back to the 12th century, were painted in the 