Follow along in the slidehsow below to see what it's like to spend a week on the water cruising one of Europe's grandest rivers.
Danube River Cruise
Danube River Cruise Through Germany, Austria and Hungary (PHOTOS)
The following photos offer a snapshot of an eight-day river cruise along the Danube. The trip begins in Nuremberg, Germany and ends in Budapest, Hungary, cruising through Regensburg, Passau, Melk, the Wachau Valley and Vienna along the way.
Viking introduced Bragi, one of its new longships, in April 2013. The interior is done up in cool tones and blonde wood, with subtle luxurious touches like padded leather railings.
The cruise begins in Nuremberg, a city dating back nearly a thousand years. The view from the Kaiserburg (Imperial Castle) takes in the old town and beyond. Approximately 90 percent of the city was destroyed during World War II and has been reconstructed.
While toy-making, gingerbread and a large Christmas market characterize Nuremberg, the city has a darker side as well. It was here that the Nazi Party rallies were held in the years leading up to World War II, and after the war it was the site of the famous Nuremberg Trials. You can now tour the rally grounds; they also double as a race track and concert venue.
Colorful flowered window boxes adorn the windows of many old town Nuremberg houses.
River cruise passengers don life jackets to practice a safety drill. Unlike ocean cruising, you're always within sight of land on a Danube river cruise.
To many passengers, a river cruise isn't just about sightseeing; it's a learning experience. Here cruisers attend an on-board lecture about the European Union as the boat sails through Germany.
As beachgoers gather for sunset, river cruisers convene on the front deck to watch the boat pass through a lock. From Nuremberg, the ship travels through the Main-Danube Canal, a 106-mile-long network of 16 locks that carry the boats over a mountain range.
A passenger watches a slideshow that features scenes from the day's land tour.
Old is new again in Regensburg, where traditional designs with a twist are a hot fashion trend. It's common to see locals running around town in neon pink dirndls covered in hearts, or board shorts styled as lederhosen.
Gold stolperstein, or "stumbling stones" are laid in the streets in Regensburg to commemorate the town's residents that were victims of the holocaust. Each stone is inscribed with a name and is usually set near the person's former address.
Regensburg's sausage tradition dates back to the middle ages, and the best place to get a taste of it is at the Historische Wurstkuchl, a 900-year-old riverside kitchen that serves nothing but sausage, sauerkraut, mustard and beer.
Leaving Regensburg, the Danube river snakes through quiet flat countryside. The banks are speckled with small towns and onion-domed churches.
River cruises are incredibly susceptible to changes in water levels. A few bridges are so low that high water makes them impassable, while low water levels make certain stretches of the Danube too shallow for cruise ships to cross. It's therefore not uncommon for your itinerary to change along the route, depending on conditions.
Many river cruise tour operators stop at the same stops -- Regensburg, Passau, Melk -- along the Danube. Each town becomes a mini cruise port when the boats come in (often around the same time of day). Crowds disembark and explore in guided tour groups, then wander or hit the souvenir shops during free time after the tour.
A colorful town at the confluence of the Danube, Ilz and Inn rivers, Passau is surrounded on almost all sides by water.
Glacial blue water flows into Passau along the Inn River. A tour group looks across to the Innstadt, which is very close to the Austrian border.
The organ in St. Stephen's Cathedral is the largest cathedral organ in the world, and regularly entertains visitors with concerts.
Floods are both a historic and present day threat to riverside towns. Buildings have lines indicating especially bad years; many date back to the 1500s. In Passau, the flooding in 2013 was one of the the worst in history, as indicated by the thin black line near the top of this marker.
You can see the stark color difference between the Inn (right, coming from the icy Alps) and Danube (left, coming from Germany's flatter terrain) rivers when they meet at the tip of Passau. The water gradually blends together down-river near the Austrian border.
Cruise ship passengers file out through the lobby to embark on a guided tour. Tour guides' narration is broadcast through headsets so even if you're not walking right next to the guide you can hear the audio.
The Benedictine Melk Abbey is perched on a cliff overlooking the Danube. After more than 900 years it remains a working monastery, with resident monks and an abbey school, but is also open to visitors.
Each room in the abbey's museum is styled according to a specific theme, some with zany color light schemes. Religious artifacts and artwork are displayed in each section.
The baroque abbey features many beautifully appointed rooms, like this former dining hall. The frescoed ceiling was painted by Paul Troger and depicts the Habsburgs -- rulers of the Holy Roman Empire -- as Greek gods.
While most touring on a river cruise is generally done by foot and boat, bus tours play a part as well. Sometimes a bus is necessary to shuttle passengers from the dock to town, other times it's a part of the tour. Occasionally if the water levels get too high or low the itinerary may shift to a bus-powered land tour.
After Melk, the Wachau Valley unveils a landscape of castles and vineyards. Jutting out over the river, Schönbühel is the first castle on the route, and is known as the "Watchman of the Wachau."
Designated a UNESCO World Heritage Site, the Wachau Valley is best seen by boat. No bridges cross the river here, vineyards practically spill off terraced cliffs into the water and stony castles present centuries of history.
Photo ops abound as the boat cruises through the valley. Here, cruisers get a good look at the market town of Spitz.
During evening cocktail hour and after dinner, the bar is where a number of cruisers come to relax. It's never very crowded though, and feels more like a place to unwind than to socialize.
Viking longships double park on the waterfront in Vienna, the second-to-last stop on the cruise.
St. Stephen's Cathedral is a hub of activity during day and night. The roof of the building is patterned with more than 200,000 glazed tiles.
This small bronze statue in Vienna's Stadtpark is the most photographed icon in the city. It depicts famous Austrian composer Johann Strauss, who's credited with making the waltz popular in Vienna.
Vienna's coffee houses are much more than places to get a caffeine fix. It's common to come, read the paper, enjoy a pastry and linger for hours.
The Hungarian Parliament Building is one of many impressive riverfront buildings in Budapest.
The best way to beat the heat in Budapest: head to one of the city's thermal bath complexes. Pools range in temperature from warm to cold, making this a popular spot all year long.
Danube river cruises go in both directions, so you can start or finish your tour in Budapest. If you want a climactic finale to your trip, choose the option that ends (rather than begins) in this splendid city.
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