7 Best Sights in The Rhineland, Germany

Cologne's landmark embodies one of the purest expressions of the Gothic spirit in Europe. The cathedral, meant to be a tangible expression of God's kingdom on Earth, was conceived with such immense dimensions that construction, begun in 1248, was not completed until 1880, after the original plan was rediscovered. At 515 feet high, the two west towers of the cathedral were briefly the tallest structures in the world when they were finished (before being eclipsed by the Washington Monument). The cathedral was built to house what are believed to be the relics of the Magi, the three kings who paid homage to the infant Jesus (the trade in holy mementos was big business in the Middle Ages—and not always scrupulous). The size of the building was not simply an example of self-aggrandizement on the part of the people of Cologne, however; it was a response to the vast numbers of pilgrims who arrived to see the relics. The ambulatory (the passage that curves around the back of the altar) is unusually large, allowing cathedral authorities to funnel large numbers of visitors up to the crossing (where the nave and transepts meet and where the relics were originally displayed), around the back of the altar, and out again.

Today the relics are kept just behind the altar, in the original, enormous gold-and-silver reliquary. The other great treasure of the cathedral, in the last chapel on the left as you face the altar, is the Gero Cross, a monumental oak crucifix dating from 971. The Altar of the City Patrons (1440), a triptych by Stephan Lochner, Cologne's most famous medieval painter, is to the right. Other highlights are the stained-glass windows, some dating from the 13th century and another, designed by Gerhard Richter with help from a computer program, from the 21st; the 15th-century altarpiece; and the early-14th-century high altar, with its glistening white figures and intricate choir screens. If you're up to it, climb to the top of the bell tower to get the complete vertical experience (at the time of writing, available by guided tour only from the Domforum at  www.domforum.de) but be aware that viewing Cologne from the Dom itself removes the skyline's most interesting feature. The treasury includes the silver shrine of Archbishop Engelbert, who was stabbed to death in 1225.

The castle ruins overlooking the town bear witness to the fact that St. Goar was once the best-fortified town in the Mittelrhein. From its beginnings in 1245, it was repeatedly enlarged by the counts of Katzenelnbogen, a powerful local dynasty, and their successors, the Landgraviate of Hesse. Rheinfels was finally demolished by the French in 1797. Take time for a walk through the impressive ruins and the museum, which has a detailed model of how the fortress looked in its heyday. It's a steep ascent by foot, but between 11 am to 5 pm, the cab company Papst will take you from the Katholische Kirche to the castle and back.

The town of Königswinter has one of the most visited castles on the Rhine, the Drachenfels. Its ruins crown one of the highest hills in the Siebengebirge, with a spectacular view of the Rhine. It's also part of Germany's oldest nature reserve, with more than 100 km (62 miles) of hiking trails. The castle was built in the 12th century by the archbishop of Cologne, and takes its name from a dragon said to have lived in a nearby cave. (The dragon was slain by Siegfried, hero of the epic Nibelungenlied.)

The castle ruins can be reached via two different hikes, each of about 45 minutes. One route begins at the Drachenfelsbahn station, and passes the Nibelungenhalle reptile zoo along the way. The other route starts at Rhöndorf on the other side of the hill. The Siebengebirge Tourist Office can provide a map that includes these and other local hiking trails.

If hiking to Drachenfels isn't for you, you can also reach the castle ruins by taking the Drachenfelsbahn, a narrow-gauge train that makes trips to the summit every half hour from March through October, and hourly in January and February. Download a free audio tour (available in English) about the Drachenfelsbahn and the Drachenfels on the website.

Just outside Düsseldorf, the Düssel River forms a valley, called the Neanderthal, where the bones of a Stone Age relative of modern man were found. The impressive museum, built at the site of the discovery in the suburb of Mettmann, includes models of the original discovery, replicas of cave drawings, and life-size models of Neanderthal Man.

This riverside museum south of the cathedral is a real hit. It recounts 3,000 years of civilization's production and enjoyment of chocolate, from the Central American Maya to the colonizing and industrializing Europeans. It's also a real factory, with lava flows of chocolate and a conveyer belt jostling thousands of truffles. The museum shop, with a huge variety of chocolate items, does a brisk business, and the riverside panorama café serves some of the best cake in town.

Königswinter's huge aquarium features 2,000 creatures from the sea. The biggest pool has a glass tunnel that enables you to walk on the "bottom of the sea." Order tickets online, which includes a necessary time-slot reservation.