Germany's fascinating underground worlds

In 1993, they were entered in the Guinness Book of Records as the "most colorful cave grottoes in the world." They were developed from a disused alum slate mine on the edge of the Thuringian Slate Mountains. The mining of the rock created underground cavities that gradually turned into a colorful world of stalactites. They feature more than 100 different shades of brown.

What at first glance looks like a Hobbit's home from the novel by Tolkien are actually dwellings dug into the sandstone. They were built in the mid-19th century by farm workers' families on the Schäferberg in the Harz Mountains. Today, the life of the last cave dweller, Ludwig Schmidt, is retold inside the apartments, which measure about 30 square meters (323 sq ft.) He left his home in 1916.

Northern Germany's only natural cave provides the largest natural winter habitat for bats in Europe. More than 30,000 animals hibernate at a constant temperature of about 9 degrees Celsius (48.2 °F) and high humidity. In order to protect the animals as much as possible, visitors are not allowed to enter Germany's northernmost limestone cave between October and March.

The most visited and largest accessible cave in Germany is located in North Rhine-Westphalia. It was discovered by chance in 1907 during a blasting. The labyrinth of stalagmites and stalactites is over 6,000 meters long. The Atta Cave is known not only for its natural wonders, but also for the Atta cheese that ripens in the passages of the dripstone cave.

The Kluterthöhle, also in North Rhine-Westphalia, was once considered the largest known cave in Germany. It consists of more than 300 passages, underground lakes and streams and is almost 6 kilometers (3.7 miles) long. Flashlight tours are available for adventurous visitors. The cave has a constant temperature of 10 degrees. This also makes it a health spa for people with asthma.

These caves are an attraction in the Saarland. For once, it was not nature that shaped them, but rather humans. They were created by the mining of red sandstone. The origin of the cave even goes back to the early Middle Ages. At that time, escape passages were driven into the Schlossberg castle hill for the Hohenburg castle above it.

A number of animal bones from the Ice Age have already been found in the dripstone cave. Among them is "Benno," a cave bear whose skeleton is on display. The age of the bones in the Franconian mountains is estimated to be up to 60,000 years. The bear bones date from the so-called Wurm Glaciation or the Weichsel Ice Age. Today, events are regularly held here, including concerts.

In Zwiefaltendorf in the Swabian Alb lies the smallest exhibition cave in Germany, it measures a whole 27 meters (88.5 feet). It was discovered in 1982 during the excavation of a cellar. It is located under the inn "Zum Rössle" and is the only access to the cave. This is a unique opportunity to combine a visit to the underworld with a visit to the inn and a guided tour of the brewery.

In Untersberg in the Berchtesgaden Alps, you'll find the longest (22.6 km/14 mi) and deepest (1149 meters/3770 ft) cave in Germany. It includes waterfalls and a 30-meter-long lake. Only scientists can access the cave, as it's been closed to visitors since a rescue operation in 2014. Its name stems from the exclamation when the cave was discovered: "Das ist ja ein Riesending!" (That's a huge one!)

Germany's only accessible ice cave is also located in the Untersberg massif, at 1,570 meters. Inside, there are about 60,000 cubic meters of ice, which is up to 30 meters thick and most of it is around 3,000 years old. Its length explored so far is 3,261 meters, of which 500 meters are accessible to visitors. However, the ice cave can only be reached by hiking for several hours.