Greiz is a town in Thuringia, and it is the capital of the district of Greiz. Greiz is situated in eastern Thuringia on the river Weiße Elster.

As with other nearby settlements, the place name (originally Grouts) is of Slavic origin and means Gradec. It was first mentioned in 1209. The prime location of Greiz at the river Weiße Elster and the stream Göltzsch made it a fast-growing town. It kept expanding during the last 1000 years. It has been recognized as town in the 13th century for the first time. Later the House of Reuss, a ruling German dynasty, built 2 castles in Greiz: the "Oberes Schloss" (Upper castle) and the "Unteres Schloss" (Lower castle). Both were built by famous architects and are still considered unique. Greiz became the capital of the Principality of Reuss-Greiz (until 1918).