1 Geyser Andernach
One of the oldest towns in Germany, Andernach is notable for several reasons: it has its own unique dialect - the "Andernacher Platt"; it houses several old industrial plants including a huge malt mill; and it is home to the world's largest cold-water geyser. The Geyser Andernach is in the Rhine Valley on a peninsula called Namedyer Werth, which you get to via a 15-minute boat journey. Driven by carbon dioxide, the 64m-high geyser was activated for the first time in 1903, shut down in 1957, then reactivated early this century as a tourist attraction. The peninsula is also home to a forest full of threatened bird species.
2 Niederwalddenkmal, Rudesheim
The riverside town of Rudesheim, on the eastern banks of the Rhine, is one of Germany's biggest tourist drawcards. It's easy to see why. The town itself is a cobblestoned postcard shot surrounded by vineyards climbing up the steep hillsides (in these parts, winemakers aren't allowed to plant vines on flat land).
Looking down on it all from high on the hilltop is the Niederwalddenkmal, a massive monument built in the 1870s to celebrate German unification. Feeling energetic? Hire a bike and head for the Niederwalddenkmal. Otherwise grab a spot in the cable car that goes up there, offering some of the Rhine's best photo opportunities.
There are two wildly contrasting museums: the Siegfrieds Mechanisches Musikkabinett is home to Germany's finest collection of data-storage musical instruments, while the Mittelalterliches Foltermuseum has impressive displays of medieval torture instruments.
3 Wurzburg Residenz
Also in Germany, the city of Wurzburg straddles both sides of the Main River, though the main town is on the eastern bank. Settled in the 4th or 5th century, it has a dark and tormented history, which includes the Wurzburg Witch Trials between 1626 and 1631 where between 600 and 900 alleged witches were burned at the stake, and mass killings of Jews in 1147 and 1298. In 1945, much of the city was destroyed in just 17 minutes by 225 British Lancaster bombers, while 5000 people died in a firestorm in the city centre. Many of the heavily damaged or destroyed buildings, including the huge Wurzburger Residenz palace, built by two prince-bishops between 1719 and 1744, were accurately reconstructed over the next 20 years, mostly by women - trummerfrauen ("rubble women") - because of the lack of men in the community following the war. The Residenz has a beautiful staircase hall with a huge fresco by Tiepolo, a Hall of Mirrors, and houses the Martin von Wagner Museum, which has an impressive collection of antiquities and a fine picture gallery. residenz-wuerzburg.de
4 Old town of Regensburg
A former medieval trading hub, Regensburg lies on the river in Bavaria, southern Germany. A Unesco World Heritage Site, the old town is known for its almost 1500 historic structures, some of which span two centuries. In among the dark, narrow lanes of the old town you'll find ancient Roman, Romanesque and Gothic buildings built from the 11th to 13th centuries, including the market, city hall and cathedral. Don't miss the 12th century stone bridge, which the knights of the 2nd and 3rd crusade used to cross the Danube on their way to the Holy Land. The building used as the construction headquarters for the bridge from 1135 AD was turned into a restaurant in 1145 AD after the bridge was finished, and these days houses the Historic Sausage Kitchen of Regensburg. Serving 6000 sausages per day, the restaurant is thought to be the oldest continuously open public restaurant in the world. wurstkuchl.de
5 Linz street festival
If you're travelling in late July you might be lucky enough to catch Pflasterspektakel, an annual street art festival, from the German words "pavement spectacle", in the Austrian city of Linz. The three-day extravaganza, held around the main square and the Landstrasse, features music, juggling, acrobatics, theatre, clowns, fire dancing, painting, and more. The city is home to a vibrant art and culture scene, so if you miss the Pflasterspektakel, there'll be something else to float your boat. pflasterspektakel.at
6 Melk Abbey
One of the most picturesque parts of the Danube is Austria's Wachau Valley, between the cities of Melk and Krems. Melk's impressive Benedictine abbey looms above the river on a rocky outcrop and is a must-visit during a stop at the ancient city. The abbey was founded in 1089 after Leopold II donated one of his castles. A monastic school, still in use today, was founded in the 12th century. The current Baroque building was built between 1702 and 1736. Don't miss the frescoes in the abbey church or the medieval manuscripts in the library. Open from March 19 to November 1. It's open for tourists daily, with or without a guided tour ($21/$18). stiftmelk.at
7 Quaff wine in Durnstein
The Wachau is also home to some of Austria's best vineyards, which you can access from the town of Durnstein. Known for its mineral-driven cool-climate white wines, the ones to go for here are gruner veltliner, riesling, and sauvignon blanc. Thirty per cent of the area's wine is made at Domane Wachau, a co-operative of local producers. The picturesque vineyards grow on steep terraces reinforced by old drystone walls - part of a World Cultural Heritage site. domaene-wachau.at
If you book flights in conjunction with selected cruises, APT is offering a deal of $795pp, flying Singapore Airlines from Auckland, Wellington or Christchurch.
A 14-day Magnificent Rivers cruise with APT from Amsterdam to Budapest costs from $7295pp twin-share.