Set where the Rhine and the Main rivers meet, Mainz is an interesting city and a good spot to try local wines. Other attractions there include the Gutenberg Museum, which tells the story of how its native son, Johannes Gutenberg, invented movable type. It also has an original Gutenberg Bible. Take time to see the Romanesque cathedral and stroll through the surrounding old town, where excavations of the city's Roman foundations are under way. Be sure to visit the gothic church St. Stephan, which has beautiful stained-glass windows created by Marc Chagall showing Biblical scenes in magical, bluish colors. Mainz is a nice day trip from Frankfurt, or you can see it before or after touring the Rhine Valley.
Neighboring
Wiesbaden also sits near the confluence of the Rhine and the Main rivers. Hot springs were the attraction for Roman soldiers, but the city's reputation as a spa and casino town pushed it to its height in the 1800s—the city still banks on that tradition. Visit the Kurhaus and Kurpark, but men will need a jacket and tie to enter the casino in the Kurhaus. For a good view of the city, take the old funicular train up the Neroberg.
Up the Rhine a little, the small town of Rudesheim, famous for its wine and nightlife, can become completely overwhelmed by its many visitors. Nevertheless, it's a charming stop. Spend an afternoon walking the small, ancient streets of the older part of town, eating in its restaurants and pausing to look at the beautiful medieval houses. Visit Siegfrieds Musik Instrumente Museum, a display of various music boxes. Also see nearby Presberg (spa resort) and the Germania monument, erected by Otto von Bismarck to commemorate the 1871 unification of Germany. Views from the monument are spectacular, but if you want to escape the crowds there, hike in the nature preserve north of it. In addition to more stunning vistas, the trails there feature castle ruins, a small zoo and buildings left from when the area was a royal hunting area in the 1800s. Many boat trips through the Rhine Valley begin at Rudesheim.
South of Mainz but close enough for a day trip is Worms (pronounced vorms, rhymes with forms). Along with Wittenberg, this Rhine River town can be said to be the birthplace of Protestantism. An assembly of churchmen, called the Diet of Worms, forced Martin Luther into hiding in 1521. Their action helped bring about the Reformation and, consequently, the formation of Protestant churches. The Kaiserdom is an important Worms landmark—it is one of the most spectacular accomplishments of medieval architecture and is worth a visit. The town also contains the oldest Jewish cemetery in Europe and an impressive Romanesque cathedral. East of Worms is the small town of Lorsch, which has the beautiful endearing door hall of an otherwise vanished Carolingian abbey. Mainz is 25 mi/40 km west of Frankfurt.