Kapfenberg is situated at an elevation of 502 m on the river Mürz. It was first mentioned in a document of around 1144 (as Chaffenberch). From the 15th century onward, hammer mills were located in Kapfenberg. The Böhler-Werke, the oldest steel industry of Central Europe, was founded here in 1864. Kapfenberg obtained the status of a town in 1924. During World War II, large parts of the town were destroyed by the bomb raids in 1943–1945.
The parish church Sankt Oswald [centre], built in Late Gothic style, was first mentioned in 1330.
The church was enlarged in Baroque style in 1752–1755. The precious Rococo interior furnishing was added after 1770.