Best known as the capital of Charlemagne's Frankish empire, today's Aachen sits at the juncture where Germany meets the Netherlands (the Dutch know it as Aken) and Belgium (where "Walloons" call it Aix-la-Chapelle). But Aachen's history goes back even further than 8th-century Charlemagne. Roman soldiers dating back to the 1st century AD cherished its hot springs (as did Charlemagne, who loved a good spa day just as much as the next guy). Aachen Cathedral, northern Europe's oldest and a UNESCO World Heritage Site, is the city's main attraction.

The old Burgundian university town of Leuven offers a range of adventures for overnight visitors or day-trippers from Bruges and Brussels. Tourists will find everything from gastronomic tours to architectural gems like the Gothic Town Hall. Nature lovers won’t be disappointed. The Kruidtuin Botanical Garden’s herbal gardens are the oldest in Belgium, and Heverleebos, a “city wood,” offers a respite for urban dwellers. The exploring is easy in Leuven, on foot or on one of the ubiquitous bikes.

Unassuming Brussels is the capital of Belgium, Flanders and Europe. Medieval Grand-Place, is indeed grand, with many 17th-century buildings and daily flower markets. Reopened in 2006, the Atomium, Brussels' Eiffel Tower, provides great views, inside and out. Architecture fans should visit Musee Horta, home of Belgian master architect Victor Horta. St. Gery's clubs and bars are packed year-round. Seafood eateries abound in Ste. Catherine. Walk, rather than get snarled up in traffic, in the narrow streets.

Eindhoven is one of the oldest cities in the Netherlands, but you’d never know it from the high-tech industry and cutting-edge design it’s currently known for. If you have kids obsessed by all things wheeled, they will love the trucks at the DAF Museum.

There are 2,000 years of history in Cologne, and visitors here will find everything from Roman towers to Gothic churches to fine examples of modern architecture. Cologne has a variety of museums, too—check out the Museum of Applied Art, the Museum Ludwig and, if you have a sweet tooth, the Chocolate Museum. Be forewarned, though—the gift shop at the latter will utterly ruin your diet.

Lively Antwerp is a hidden gem. Its medieval streets, Renaissance monuments and vibrant nightlife tend to be overshadowed by its reputation as center of the diamond trade and as the world's fifth-largest port. Biking is a popular choice for getting around this stylish Flemish city. See thousands of Old Masters at the Royal Museum and Rubens House. Experience the bustle of life at the Grote Markt. Marvel at the art and architecture of the still unfinished Cathedral of Our Lady, started in 1351.

The capital of North Rhine-Westphalia, Dusseldorf is a regional economic powerhouse straddling the banks of the Rhine River. Altstadt is not just Dusseldorf's lovely old town, but also where the city's nightlife is based and where Altbier, its native dark beer, is plentiful. Dusselforfians take their beer seriously. Königsallee (Ko to the locals), Dusseldorf's famous shopping street, has many high-end stores. And the Museum Kunst Palast has one of the Rhineland's best art collections.

Though probably best known as the capital of West Germany from 1949 to 1990 (and of reunified Germany until 1999), Bonn actually has a history dating back to the 1st century BC. Roman soldiers were stationed here and the largest known Roman fort was built at Bonn. In medieval times, the town gained prominence when the Archbishop of Cologne transferred his seat to Bonn. The city's most famous son is Ludwig van Beethoven, born in 1770 at Bonngasse, where a museum now honors him.

A captivating contrast of old and new, Luxembourg City's past is celebrated by its World Heritage status; its present sway by its position as headquarters for several significant European institutions. Small enough to explore on foot, this compact city offers a wealth of attractions, including dramatic promontory The Bock, underground passages in Petrusse Casemates, Palace of the Grand Dukes and the National Museum. Countless banks on Boulevard Royal, once a fortress moat, hint at the duchy's wealth.