The stones are not solid brass. There is a thin plaque of metal mounted on top of a concrete base. They are made exclusively by artist Gunter Demnig, who began the project in Cologne, Germany, in 1992. By the end of 2019, there were 75,000 stones across Europe. The first stones were placed in the Czech Republic in Prague’s Josefov district in 2008. Aside from Prague, they can be found in Brno, Olomouc, and Ostrava plus some smaller towns.