© Shutterstock 

Cochem Castle, Germany -

Cochem Imperial Castle lends a noble perspective to the quaint town of Cochem, in Germany's Rhineland-Palatinate. It's been guarding a section of the Moselle river since the 12th century.

© Shutterstock 

Malbork Castle, Poland -

Malbork holds the distinction of being the largest castle on the planet by land area. A UNESCO World Heritage Site, the fortification overlooks the Nogat river, a tributary of the Vistula River.

© Shutterstock

Almourol Castle, Portugal -

Picture-perfect Almourol Castle crowns an island in the middle of the Tagus River in central Portugal. It dates back to the late 12th century.

© Shutterstock 

Loket Castle, Czech Republic -

Surrounded on three sides by the Ohre river, beautiful Loket Castle is one of the oldest and most valuable historical stone fortifications in the country, dating back as it does to the early 13th century.

© Shutterstock 

Hohensalzburg Fortress, Austria -

Hohensalzburg Fortress is one of the standout landmarks of Salzburg. It's grandly set above the Salzach river.

© Shutterstock 

Muiden Castle, Netherlands -

Muiden Castle is sited at the mouth of the Vecht river, some 15 km (9 mi) southeast of Amsterdam. It was completed in 1370.

© Shutterstock 

Czocha Castle, Poland -

The fairy-tale Czocha Castle in Poland's Lower Silesia province is also surrounded on three sides by a river, the meandering Kwisa.

© Shutterstock 

Conway Castle, Wales -

The UNESCO World Heritage Site that is Conway Castle stands over the mouth of the River Conway near what was once a strategic military crossing point in North Wales during the Middle Ages.

© Shutterstock 

Tower of London, England -

One of Great Britain's most illustrious historical monuments, the Tower of London has been an ubiquitous feature on the River Thames since the 11th century.

© Getty Images

Wertheim Castle, Germany -

Built in the 12th century, Wertheim Castle is perched regally on the crest of a hill above the valleys of the Main and Tauber rivers. The castle crowns the town of Wertheim am Main in Germany's Baden-Württemberg state.

© Shutterstock 

Château de Chenonceau, France -

One of the best-known châteaux of the Loire Valley, the fortified Château de Chenonceau spans the Cher river, near the small village of Chenonceaux. It was built in the 16th century.

© Shutterstock 

Heidelberg Castle, Germany -

Dominating the Heidelberg skyline is this early 13th-century castle, among the most important Renaissance structures north of the Alps. It looms over the Neckar river in south-west Germany.

© Shutterstock 

Golubac Fortress, Serbia -

A favorite Danube river sightseeing landmark, Golubac Fortress in eastern Serbia is one of the best-preserved medieval castles in Europe.

© Shutterstock 

Melk Abbey, Austria -

Melk Abbey was founded in 1089 and originally served as a castle, built over the Danube river to defend the approach to Melk, in Lower Austria.

© Shutterstock 

Warwick Castle, England -

One of England's great medieval castles, Warwick was originally built by William the Conqueror in 1068. Its weather-worn ramparts overlook the River Avon in Warwickshire.

© Shutterstock 

Château de Sully-sur-Loire, France -

Château de Sully-sur-Loire stands as a fine example of a château-fort, a true castle, built to command one of the few sites where the Loire river can be crossed. Its foundations date back to the 14th century.

© Shutterstock 

Buda Castle, Hungary -

Overlooking the Danube river, Buda Castle stands on foundations dating back to 1265. The site was expanded in the 18th century as a palace complex to accommodate the Hungarian kings in Budapest.

© Shutterstock 

Bratislava Castle, Slovakia -

Built on a hill above Bratislava's Old Town district, this showpiece castle is one of the gems in the Slovakian tourism crown. It stands over the Danube river.

© Shutterstock 

Le Palais de I'lle, France -

Annecy, in France's Auvergne-Rhône-Alpes region, is home to the diminutive Le Palais de I'lle, a medieval castle that later served as a prison. Today it's a museum and actually sits in the middle of the Thiou Canal.

© Shutterstock 

Mértola Castle, Portugal -

This splendid, well-preserved castle commands views across the Guadiana River in Portugal's Alentejo province. It once served as stronghold for the Moors in the 12th century before falling to Christian forces in 1238 during the Reconquista.

© Shutterstock 

Château Gaillard, France -

This impressive medieval castle ruin still stands guard over Les Andelys and the Seine river in France's Normandy region.

© Shutterstock 

Marksburg Castle, Germany -

Medieval Marksburg Castle is perched above the town of Braubach in Rhineland-Palatinate. It's one of the principal sites of the Rhine Gorge UNESCO World Heritage Site.

© Shutterstock 

Alcázar of Toledo, Spain -

The high point of any visit to Toledo is, quite literally, discovering the magnificent fortress known as the Alcázar of Toledo. Sitting above the city, views from towers take in the Tagus River below.

© Shutterstock 

Windsor Castle, England -

Perhaps the most famous castle in the world, Windsor is one of the residences of the British royal family. In fact, it was the main residence of Queen Elizabeth II from 2011 until her death in 2022, and its where the late monarch was laid to rest. The historic market town of Windsor is fronted by the River Thames.

© Shutterstock 

Château de Castelnaud, France -

Summiting a rocky outcrop overlooking scenic Castelnaud-la-Chapelle, this medieval fortress affords uninterrupted views of the Dordogne river in Périgord, southern France.

© Shutterstock 

Castle of Serravalle, Italy -

The little-visited Castle of Serravalle has been standing over the pretty Sardinian town of Bosa since the 12th century.

© Shutterstock 

Orebro Castle, Sweden -

Some of the chunky, sturdy walls of Orebro Castle date back to the 13th century. The medieval castle fortification is set over the Svartån river, and since 1764 has served as the grand residence of the governor of Örebro County.

© Shutterstock 

Orlik Castle, Czech Republic -

Standing just above the waterline, Orlik Castle was established as a royal fortification in the late 13th century, originally to guard a ford over the Vltava river.

© Shutterstock 

Château de Saumur, France -

Originally constructed in the 10th century as a castle but rebuilt in 1067 to resemble its current rather palatial appearance, Château de Saumur is named after the French town of Saumur, located between the Loire and Thouet rivers.

© Shutterstock 

Olavinlinna Castle, Finland -

A cherished Finnish landmark, historic Olavinlinna Castle is built on an island in the Strait of Kyrönsalmi between two lakes. The castle serves as a spectacular stage for the annual Savonlinna Opera Festival. 

Sources: (UNESCO) (BBC)

See also: Scenic journeys along the strait and narrow. 

© Shutterstock