The Rhine River: Fairy-tale castles, picturesque towns (like Germany's Bacharach, above), and a Black Forest setting straight out of the Brothers Grimm.
The Rhine River: The source of the river, Tomasee lake, in Grisons, Switzerland.
The Elbe River: Rugged cliffs and sandstone formations, flecked with baroque cities and wine villages.
The Elbe River: The fortress Königstein in Saxony.
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The Volga River: Multicolored, onion-dome cathedrals (like this temple in the city of Uglich) and ornate palaces fit for a czar.
The Volga River: A flooded bell tower in Kalyazin, Russia.
The Dnieper River: Tranquil Ukrainian countryside, dotted with birch and pine forests, that gives way to the elegant gold domes of Kiev (above).
The Dnieper River: Kiev, the capital city of Ukraine.
The Danube River: Stretching from the BlackForest to the Black Sea, it's the grande dame of rivers, seen here at the Iron Gates gorge between Romania and Serbia.
The Danube River: The Chain Bridge in the Hungarian capital of Budapest.
The Rhone River: Food lovers’ territory, through the wine regions of Burgundy, the lavender fields of Provence, and the culinary capital of Lyon.
The Rhone River: Lavender fields and vineyards in France's Rhone-Alpes region.
The Douro River: The terraced vineyards of the world's oldest demarcated wine country (above), where Portugal's sweet, sticky port is made.
The Douro River: Port wine vineyards in Portugal's Douro region.
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The Seine River: The City of Light (above, as viewed from the Eiffel Tower) and the serene Normandy landscapes that inspired Monet.
The Seine River: The riverside town of Samois-sur-Seine, France.
With bookings up over 200 percent in the past decade, river cruising has never been bigger, especially along the old-country routes of Europe. Here's a look at the most popular routes.