Confluence of the Vorderrhein and Hinterrhein

Confluence of the Vorderrhein and Hinterrhein, Reichenau
Dominated by Reichenau Castle, the hamlet lies at the confluence of the Vorderrhein and Hinterrhein rivers, making it virtually the birthplace of the Rhine.
It all began 10,000 years ago. Between the Flimserstein (a high plateau) and Piz Grisch, over 10,000 cubic meters of rock broke off and thundered down into the valley. Towards Reichenau, the Vorderrhein valley disappears under a gigantic mass of rubble. From there, the Rhine diligently ate its way through the rock, creating the spectacular Swiss "Grand Canyon" – the Ruinaulta.
Text / Source: myswitzerland.com
myswitzerland.com/de-ch/erlebnisse/route/vom-zusammenfluss-der-rheine-in-die-rheinschlucht

Ruinaulta Rhine Gorge
The Ruinaulta, or Rhine Gorge, is a gorge of the Vorderrhein River, up to 400 meters deep and approximately 13 kilometers long, between Ilanz and the mouth of the Hinterrhein River near Reichenau in the canton of Graubünden in Switzerland. The Romansh name 'Ruinaulta' is composed of the two words ruina (scree slope, quarry) and aulta (high).
The Ruinaulta was formed after the Flims Landslide almost 10,000 years ago. At that time, over 10 billion cubic meters of rock broke off between the Flimserstein and Piz Grisch, burying the Vorderrhein Valley between the present-day villages of Castrisch and Reichenau under a mass of debris several hundred meters thick.
Because the Vorderrhein River could no longer drain away, a lake was dammed over a length of approximately 25 kilometers. Over time, the river cut deep into the landslide, and the resulting lake drained away completely. What remained was the Ruinaulta, with its steep limestone scree cliffs in impressive erosion formations.
Text / Source: Wikipedia
de.wikipedia.org/wiki/Ruinaulta

In addition to Reichenau Castle and the bridge, the confluence of the Vorder and Hinterrhein rivers is another highlight of the small town. Especially the wide confluence should definitely be visited if you are in the vicinity.