Contrary to popular belief, (most) castle walls (interior and exterior) weren't bare stone, as depicted in many films, books and paintings. Like the building depicted, they were covered with a layer of lime (recipes and colours varied between locations). This way a castle looked more beautiful and caught the eye from far away, furthermore with the interior walls coated in white, light would bounce around the rooms and hallways, making the interior much brighter. Bedroom walls and great halls were also covered with beautiful and intricate paintings