The Plessur is a 33 km long right tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Rhine River running through the Swiss canton of Graubünden

Graubünden

Graubünden or Grisons is the largest and easternmost canton of Switzerland. The canton shares borders with the cantons of Ticino, Uri, Glarus and St. Gallen and international borders with Italy, Austria and Liechtenstein...

. The river source is near the municipality of Arosa

Arosa

Arosa is a town and a municipality in the district of Plessur in the canton of Graubünden in Switzerland. It is both a summer and a winter tourist resort.-History:...

 in the Plessur Range

Plessur Range

The Plessur Range is a mountain range in the Alps of eastern Switzerland. It is considered to be part of the Central Eastern Alps. It is named after the river Plessur, which originates from the center of the ranges...

. It then flows through the Schanfigg valley before emptying into the Rhine at Chur

Chur

Chur or Coire is the capital of the Swiss canton of Graubünden and lies in the northern part of the canton.-History:The name "chur" derives perhaps from the Celtic kora or koria, meaning "tribe", or from the Latin curia....

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The Langwieser Viaduct

Langwieser Viaduct

The Langwieser Viaduct is a single track reinforced concrete railway bridge spanning the Plessur River and the Sapünerbach, near Langwies, in the Canton of Graubünden, Switzerland....

, an early reinforced concrete

Reinforced concrete

Reinforced concrete is concrete in which reinforcement bars , reinforcement grids, plates or fibers have been incorporated to strengthen the concrete in tension. It was invented by French gardener Joseph Monier in 1849 and patented in 1867. The term Ferro Concrete refers only to concrete that is...

 railroad bridge constructed in 1914, spans the Plessur near the municipality of Langwies

Langwies

Langwies is a municipality in the district of Plessur in the canton of Graubünden in Switzerland.-Geography:Langwies has an area, , of . Of this area, 48.8% is used for agricultural purposes, while 22.6% is forested...

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