Salgótarján (shŏlˈgōtŏrˌyän) [key], city (1991 est. pop. 47,500), N Hungary, near the Slovak border. It is an industrial center with ironworks, glassworks, and manufactures of agricultural machinery. Salgótarján was a small settlement that grew rapidly after the discovery of coal there in the early 19th cent. Nearby, on a basaltic hill, are the ruins of a medieval fortress.