Wikipedia
A stolperstein ( from German, literally "stumbling stone", plural stolpersteine) is a cobblestone-size concrete cube bearing a brass plate inscribed with the name and life dates of individual victims of German Nazism. The stolperstein art project was initiated by the German artist Gunter Demnig in 1992, and is still ongoing. It aims at commemorating individual persons at exactly the last place of residency – or, sometimes, work – which was freely chosen by the person before he or she fell victim to Nazi terror, euthanasia, eugenics, was deported to a concentration or extermination camp, or escaped persecution by emigration or suicide. , over 50,000 stolpersteine have been laid in 18 European countries, making the stolperstein project the world's largest decentralized memorial.
The majority of stolpersteine commemorate Jewish victims of the Holocaust. Others have been placed for Sinti and Romani people (then also called "gypsies"), homosexuals, Jehovah's Witnesses, black people, members of the Christians opposition (both Protestants and Catholics), the Communist Party and the European anti-Nazi Resistance, military deserters, and the physically or mentally disabled.