Short answers, pulled from the story.
The Rhine begins its journey in the Swiss canton of Graubünden where two distinct streams merge to form the river's true identity. The Anterior Rhine springs from Lai da Tuma near the Oberalp Pass while the Posterior Rhine rises from the Paradies Glacier below the Rheinwaldhorn.
Tectonic plates shifted millions of years ago to create the Upper Rhine Graben a massive rift system stretching between southwest Germany and eastern France. During the Miocene period a primitive river system developed within this graben though it did not yet carry water from the Alps.
Augustus ordered his stepson Drusus to establish fifty military camps along the river in 12 BC initiating the Germanic Wars. Between AD 14 and 180 eight legions were stationed at five bases along the river including Vetera at Xanten and Argentoratum at Strasbourg.
The river descends 203 meters over nearly 86 kilometers passing towns like Chur and Sargans along the way. At Sargans a natural dam only a few meters high prevents the water from flowing into Lake Walen or Lake Zurich instead it empties into Lake Constance on Austrian territory.
UNESCO designated the Rhine Gorge between Rüdesheim am Rhein and Koblenz as a World Heritage Site under the name Rhine Gorge in 2002. This stretch features more than forty castles and fortresses from the Middle Ages lining the steep slopes above the water.