Six of the most spectacular buildings in on the Rhine, Main and Danube rivers

Namedy Castle.

A cruise between Amsterdam and Budapest along the Rhine, Main and Danube rivers takes you past some of central Europe's most eye-popping buildings.

NAMEDY CASTLE, ANDERNACH, GERMANY

Many of Germany's castles are state property, but this moated masterpiece on a picturesque section of the Middle Rhine remains the family home of Princess Heide von Hohenzollern, which adds personal atmosphere to its considerable history. A comfortable 19th-century residential wing sits beside the medieval castle core that has a splendid red-walled Knights' Hall cluttered with armour. In one of APT's Signature Experiences on its popular 15-day Magnificent Europe cruise, you're welcomed by the princess and, after exploring, enjoy morning tea, or a cocktail party in the ballroom. See burg-namedy.com

EHRENBREITSTEIN FORTRESS, KOBLENZ, GERMANY

Credit: GNTB

This whopping, part-ruined Prussian citadel is one of Europe's largest fortresses, slumped on a rocky outcrop across the Rhine from medieval trading town Koblenz. A cable car near the cruise-ship dock will waft you across the river to see it, which is worth the ride for splendid views onto Deutsches Eck (Germany's Corner) at the confluence of the darker Rhine and pretty blue Moselle rivers. Permanent exhibitions cover the fort's history and regional archaeology and wine, but the citadel is liveliest when hosting regular festivals and music events. See tor-zum-welterbe.de

MARIENBERG FORTRESS, WURZBURG, GERMANY

Local dukes first knocked up a small fort and still-existing chapel on this hill in the eighth century. Then Wurzburg's independent prince-bishops spent a happy half-millennium adding walls, bastions, towers, residential quarters and an arsenal to produce the mighty fortress that dominates the Main River. Although menacing, its brute force and size is relieved by baroque-era garden terraces, pretty with parterres where marigolds and roses flourish and mythological figures spit water. Skirts of vines soften lumpen grey bastions, and views over the valley are splendid. See schloesser.bayern.de

MELK ABBEY, MELK, AUSTRIA

Credit: iStock

This supersized monastery sits in a mustard-yellow pile on a bluff above the strategic western end of Austria's Danube valley. Benedictine monks have lived here since the 11th century, but an outrageous baroque-era renovation rescue created the bling-laden building you see today, groaning with gilt, gold, marble and portraits of glum Austrian emperors. The library's ceilings swirls with fat-bummed cherubs, while grinning skeletons in glass church cases remind you that all is vanity. Between statues of saints on the terraces you get fine views over Melk's pastel-coloured houses and the Danube River. See stiftmelk.at

LIECHTENSTEIN CITY PALACE, VIENNA, AUSTRIA

Vienna is renowned for palaces, and this superbly renovated gem, owned by Liechtenstein's royal family, is one of its best examples. It was Vienna's first major baroque building and set the tone with its over-the-top stucco, gold leaf, artworks and glittering chandeliers. The rooms are magnificent, though the sweeping baroque staircase is even more eye-catching. On an APT cruise, guests enjoy an exclusive cocktail party and private recital at the palace, during which a full orchestra plays music by Mozart and Strauss, and members of the Mozart Boys' Choir give an opera recital. See palaisliechtenstein.com

PARLIAMENT HOUSE, BUDAPEST, HUNGARY

Credit: iStock

Budapest provides one of the best arrivals in river cruising and the panorama's centrepiece is the enormous waterfront building that houses the National Assembly. If it reminds you of Britain's Palace of Westminster that's no coincidence, since it shares the same neo-Gothic architecture, but Budapest's version is softer and more romantic. You'll want to walk around and admire its fripperies from every angle, but no vantage point beats the deck of a cruise ship as it drifts past Parliament House in all its majesty. You can tour parts of the interior, which has Renaissance-inspired decor. See parlament.hu