• The Rhine has over 35 tributaries.Rhine river image by Tatiana Mikheeva from Fotolia.com
  
  Germany's best-known river, the Rhine, has approximately 40 tributaries from its source to its mouth. At 820 miles, the Rhine is one of Europe's longest rivers. The name "Rhine" comes from the Celtic word "Renos," which literally means "that which flows." The Rhine's source is in the Swiss mountains, and the river flows north along the French/German border, into Germany to its mouth in the Netherlands.
  
  

Main

• The Main is one of the Rhine's most significant tributaries. It flows from the Bavarian mountains to join the Rhine at its halfway point. The Main flows through the large German city of Frankfurt and is approximately 324 miles long from its source to its meeting with the Rhine. Visitors to Frankfurt often choose to take a short boat trip on the Main to see the city from the water, or a longer cruise between Frankfurt and Wurzburg.
  
  

Mosel

• The longest tributary of the Rhine, the Mosel River's source is in the French mountains. The river then flows for 332 miles through Luxembourg and into Germany, where it meets the Rhine at the town of Koblenz. The banks of the Mosel Valley in Germany are lined with vineyards that produce fine wines. The Mosel is famous for its scenery and castles. The river runs through Germany's oldest documented city, Trier. The smaller towns of Bernkastel and Cochem attract visitors for sightseeing and wine-tasting.
  
  

Neckar

• The Neckar is a 228-mile tributary to the Rhine, with its source in Germany's Black Forest region. Castles, vineyards and forests line the banks of the Neckar, which attracts visitors for cycling, hiking and boating. The Neckar runs through the well-known German towns of Heidelberg and Stuttgart.
  
  

Meuse

• The Meuse River's source is on the Langres plateau in France. The river runs through France for 280 miles, then through Belgium for 119 miles. It enters the Netherlands, where it joins part of the Rhine south of the town of Nijmegen in a shared delta. In Belgium, the Meuse flows mainly through the French-speaking part of the country, through the towns of Namur and Liege. The river also flows through the Flemish part of Belgium, lending its Dutch name of Maas to towns Maasmechelen in Belgium, and Maastricht in the Netherlands.