Destination Danube: Four Countries & Hungary National Day

Situated along the Route of Emperors and Kings where the Danube, Inn, and Ilz Rivers meet, Passau was settled as early as the Neolithic Age. During the Renaissance, this City of Three Rivers was a major manufacturing center of swords, crafting bladed weapons stamped with the Passau wolf, which legend claimed would grant invulnerability. Today, the most famous sights lining the narrow cobblestone streets of the Old Town are the artistic Town Hall and the Baroque St. Stephen's Cathedral with its green-domed towers and one of the largest organs in the world.

Grein is primarily known for its castle, which has been towering over the river for 500 years. The former hunting castle features a knights' hall, stone theater lined with Renaissance-era pebbles from the river, and diamond vault. Grein is also home to Austria's oldest still-active theater, which is filled with oddities, like locking front-row seats, a curtained-off toilet right in the theater so audience members wouldn't miss the performance, and a "jail seat" where prisoners could watch the show through a window!

No visit to the Wachau Valley is complete without visiting Austria’s prettiest abbey. Built on a rocky promontory overlooking the Danube, Melk Abbey's origins date back to 1089. Today, it is one of Europe's finest examples of Baroque architecture, where Benedictine monks still farm the land and operate what is now the oldest school in Austria. Highlights include the library of ancient manuscripts, frescoed ceiling, stunning spiral staircases, and the ornate abbey church.

Vienna is a city that defies simple description. Over the centuries, it has been an imperial city, seat of the Holy Roman Empire, capital of the Austro-Hungarian Empire, and capital of sovereign Austria. Today, Vienna retains the grand Baroque architecture, historic style, and Lebenskunst (art of living) that attracted famous composers like Mozart and Strauss. It's a wonderland of lavish palaces and cathedrals, world-class museums and music venues, atmospheric coffee houses, and romantic fiakers (horse-drawn carriages) clip-clopping past it all.

Capital of Hungary from the 10th to mid-13th centuries, the royal city of Esztergom is where St. Stephen, Hungary's first king, was crowned. Esztergom Basilica, the country's largest church and seat of the Catholic Church in Hungary, houses the nation's largest ecclesiastical collection, while Esztergom Castle sits majestically on a cliff overlooking the Danube. Meanwhile, the city's medieval center is walled by Baroque, Rococo, and Neoclassical buildings and features a lively market square whose houses were occuped by rich merchants in the 17th century.

Visegrád is a small Hungarian castle town, just north of Budapest on the right bank of the Danube. In 1325, King Charles I of Hungary named Visegrád the country's royal seat; however, that honor transferred to Buda around 1405. It is known for its beautiful medieval fortress (Upper Castle); remains of an important Roman fort built in the 4th century; Lower Castle with the hexagonal Solomon Tower; and the 14th-century Royal Palace with its Gothic cloister. The town is also popular for its thermal spas and excellent Hungarian cuisine, including hearty stews, grilled meats, and superb local wines.

One of the most beautiful cities in the world, the wonders of Budapest rise up along both banks of the Danube in a truly impressive way. Along with Heroes' Square with its Tomb of the Unknown Soldier, awe-inspiring Hungarian Parliament Building, and the lavish Castle District with photogenic Fishermen's Bastion, the city is home to a captivating Jewish district and the second-largest synagogue in the world, an intricate underground cave system, and some of Europe's most famous thermal baths.

Bratislava is perfect for those who want to be transported to another time. Even from a distance, its 9th-century clifftop castle strikes an impressive pose. Down below, the bustling pedestrian-only Old Town is a charming collection of Old World architecture, like Michael's Gate, St. Martin's Cathedral, the Old Opera House, and the Neoclassical Primate's Palace. There's even a surprise or two, with Napoleon's cannonballs lodged in historic walls and an unexpected statue of Cumil the Sewer Worker peering up from below street level!