"Gradec", Slovene for 'little castle', was first mentioned in a 1091 deed, then part of the Imperial March of Styria. The prefix "Windisch" (the traditional German name for Slavs in general and Slovenes in particular) was added to distinguish it from the city Graz (whose name has the same etymology). The modern Slovene name, Slovenj Gradec (literally: the Slovene Graz), derives from this German denomination. From 1180 until 1918, Slovenj Gradec belonged to the Duchy of Styria, since 1804 a crown land of the Austrian Empire. It was the ancestral seat of the Windisch-Graetz noble family first documented in 1220. Upon the dissolution of Austria-Hungary in 1918, with the rest of Lower Styria, it was included in the newly established Kingdom of the Serbs, Croats and Slovenes.