The "Stones of Truth", the stones of "forgetfulness", of memory, is a great monument that spreads to more than 20 countries in Europe. The "Stolperstein" is the largest decentralized monument in the world and is the inspiration of the German artist Guider Demnich, who makes bronze plaques that are placed in places where they lived victims of Nazi atrocities, stating their details. In Greece, the Stones of Truth were placed on the sidewalk in front of the 1st High School of Thessaloniki. In 1943, 149 of his Jewish students were sent to concentration camps, of which only 6 survived. Apostolos Dereklis, an immigrant in Germany, fought for the placement of the tiles in Thessaloniki, being the same graduate of the 1st Gymnasium today Petres in front of the school is part of the more than 75,000 small monuments across Europe that make up Stolperstein.