Feuerstein Castle (German: Burg Feuerstein) lies at the edge of the so-called Lange Meile near Ebermannstadt in the county of Forchheim in the south German state of Bavaria. It was built in 1941 by Oskar Vierling as a laboratory for researching High Frequency technology and electroacoustics and was used until 1945 by 250 employees for research into weapons and communication technology as part of the German armaments programme during the Second World War.