Castle Babelsberg

Babelsberg Castle, considered the main castle in Park Babelsberg but only one of several, is located in Germany and was originally built as a small summer palace for Prince William of Prussia circa 1800s. It later served as a paleontology museum from 1966 until the end of the Cold War. Today the location is part of the Potsdam World Heritage Site.

Mammoth Cave National Park

A cave or cavern is a natural underground space large enough for a human to enter. Some people suggest that the term cave should only apply to cavities that have some part that does not receive daylight; however, in popular usage, the term includes smaller spaces like sea caves, rock shelters, andgrottos.

Mammoth Cave National Park

Mammoth Cave National Park is a U.S.  Park in central Kentucky, comprehensive portions of Mammoth Cave, the longest cave system known in the world. The official name of the system is the Mammoth-Flint Ridge Cave System for the ridge under which the cave has formed. The park was established as a national park on July 1, 1941. It became a World Heritage Site on October 27, 1981, and an international Biosphere Reserve on September 26, 1990.

The park’s 52,835 acres (21,382 ha) are located primarily in Edmonson County, Kentucky, with small areas extending eastward into Hart County and Barren County. It is centered around the Green River, with atributary, the Nolin River, feeding into the Green just inside the park. With over 367 miles (591 km) of passageways it is by far the world’s longest known cave system, being well over twice as long as the second longest cave system, which is South Dakota‘s Jewel Cave with just over 150 miles (240 km) of known passageways.

Castle Heemstede

Heemstede castle was completed in 1286 on the spaarne river by Dirk van Hoylede in the province of North Holland, Netherlands. It has been built, burned down and rebuilt several times over the centuries and it was last torn down in 1810, after years of neglect. Today it is a restaurant.