Germany's 10 most eye-catching castles

Marksburg Castle high above the town of Braubach on the Rhine River is believed to date back to the early 12th century - and has remained intact to this very day. It's the only castle built on a hill along the Middle Rhine Valley that was never destroyed. Since 2002, the Upper Middle Rhine Valley is listed as a UNESCO World Heritage Site. On average, you'll see a castle every 2.5 kilometers.

It's arguably Germany's most important castle. Built around 1067 above the central German town of Eisenach, Wartburg provided sanctuary to a fleeing Martin Luther in 1521-22. Here, he translated the New Testament into German. In 1206 it featured the legendary minstrel singing contest portrayed in Richard Wagner's opera "Tannhäuser." Wartburg has been a UNESCO World Heritage Site since 1999.

In medieval times, Nuremberg Castle was a prominent imperial palace. Emperors and Kings of the Holy Roman Empire resided here over the centuries. Demolished in World War II, the castle was rebuilt true to its historic architecture.

Eltz Castle featured prominently on the back of Germany's 500 Deutsche Mark note, making it one of the country's best known castles. Built in the early 12th century in a spectacular location at the top of a 70-meter (230-foot) rock spur in the hills above the Moselle River, Eltz Castle today is a tourist magnet.

Perched above the town of Burghausen in Upper Bavaria, it is the longest castle complex in the world, at least according to the Guinness Book of Records: it measures 1051 meters. The castle was built before 1025 and served as a residence to the Bavarian Wittelsbach dynasty.

First mentioned in 1323, Rheinstein Castle is also situated in the Upper Middle Rhine Valley. In 1823, builder and architect Karl Friedrich urged Prince Friedrich of Prussia to buy the castle that had fallen into disrepair in the late 16th century. In the Romantic period, Rheinstein Castle was the first Rhine River castle to be reconstructed.

It's the largest castle built on a hill along the Moselle River and is a prominent landmark for the town of Cochem. Cochem Castle was presumably built around the year 1100 and destroyed in the 17th century. Berlin entrepreneur Louis Ravené bought it for 300 gold marks and rebuilt the castle in neo-Gothic style around 1877, according to the romantic notions of a knights' castle.

In 1914, teacher Richard Schirrmann opened the world's first youth hostel here. Altena Castle in North Rhine-Westphalia is over 800 years old. After falling into disrepair over the centuries, its reconstruction was completed in 1918.

One of the best-preserved German castles with a moat can also be found in North Rhine-Westphalia. Called the Satzvey Castle, it dates back to the 12th century. Daunting moats were dug to keep hostile enemies at bay. In flat regions, they were an alternative to perching the castle on a rocky cliff or hill.

The spectacular appearance of Hohenzollern Castle in this photo is due to the effects of thermal inversion. The structure lies atop the 855-meter mountain of the same name in Baden-Württemberg. In 1850, Prussian rulers had the one-time residence of their ancestors rebuilt in its current, idealized form. Rulers of the German Empire were drawn from the Hohenzollern dynasty from 1871 to 1918.