Basel is a city on the Rhine River in northwest Switzerland, close to the country’s borders with France and Germany. Its medieval old town centers around Marktplatz, dominated by the 16th-century, red-sandstone Town Hall. Its 12th-century Gothic cathedral has city views, and contains the tomb of the 16th-century Dutch scholar, Erasmus. The city’s university houses some of Erasmus’ works.

Breisach is a town with approximately 16,500 inhabitants, situated along the Rhine in the Rhine Valley, in the district Breisgau-Hochschwarzwald, Baden-Württemberg, Germany, about halfway between Freiburg and Colmar — 20 kilometres away from each — and about 60 kilometres north of Basel near the Kaiserstuhl.

Strasbourg is the capital city of the Grand Est region, formerly Alsace, in northeastern France. It's also the formal seat of the European Parliament and sits near the German border, with culture and architecture blending German and French influences. Its Gothic Cathédrale Notre-Dame features daily shows from its astronomical clock and sweeping views of the Rhine River from partway up its 142m spire.

Rüdesheim am Rhein is a town in the Rhine Valley, Germany. It’s known for winemaking, especially of Riesling wines. In the center, Drosselgasse is a lane lined with shops, taverns and restaurants. Nearby, Siegfried’s Mechanical Music Cabinet is a museum of automated musical instruments. Medieval Brömserburg Castle is home to the Rheingau Wine Museum, exhibiting wine paraphernalia from ancient times to the present.

Cologne, a 2,000-year-old city spanning the Rhine River in western Germany, is the region’s cultural hub. A landmark of High Gothic architecture set amid reconstructed old town, the twin-spired Cologne Cathedral is also known for its gilded medieval reliquary and sweeping river views. The adjacent Museum Ludwig showcases 20th-century art, including many masterpieces by Picasso, and the Romano-Germanic Museum houses Roman antiquities.

Mainz is a German city on the Rhine River. It’s known for its old town, with half-timbered houses and medieval market squares. In the center, the Marktbrunnen is a Renaissance fountain with red columns. Nearby, a distinctive octagonal tower tops the Romanesque Mainz Cathedral, built of deep red sandstone. The Gutenberg Museum honors the inventor of the printing press with exhibits, including 2 of his original bibles.

Frankfurt, a central German city on the river Main, is a major financial hub that's home to the European Central Bank. It's the birthplace of famed writer Johann Wolfgang von Goethe, whose former home is now the Goethe House Museum. Like much of the city, it was damaged during World War II and later rebuilt.