The Thuringian Forest ("Thüringer Wald" in German), is a mountain range in the southern parts of the German state of Thuringia, running northwest to southeast. Skirting from its southerly source in foothills to a gorge on its north-west side is the Werra valley. On the other side of the Forest is an upper outcrop of the North German Plain, the Thuringian Basin, which includes the city Erfurt. The south and south-east continuation of the range is the highland often called the Thuringian-Vogtlandian Slate Mountains.