I found these engraved brass cobblestones on sidewalks throughout Cologne, Germany, when I lived there a few years ago. The stones are memorials to residents of buildings that were displaced during World War II to concentration camps. I saw the artist responsible for this intervention, Gunter Demnig, speak at our infoshop back in 2001. The name of the project, Stolpersteine, translates to “stumbling stones.” Demnig has by now installed more than 12,000 stones in roughly 270 German towns and cities since 1996. This piece, in its subtlety and intimacy with everyday behavior, brings the sometimes abstract death and horror of the Holocaust to the concrete reality of the individuals who were destroyed.
For more information, there is a great article in Smithsonian magazine that you can check out here: http://www.smithsonianmag.com/people-places/stolpersteine.html