The Plessur is a river, 33 km long, and a right tributary of the Rhine running through the Swiss canton of Graubünden. Its head is near Arosa in the Plessur Range. It then flows through the Schanfigg valley before emptying into the Rhine at Chur.
The Langwieser Viaduct, an early reinforced concrete railway bridge constructed in 1914, spans the Plessur near Langwies.
