Shell Grotto
> Location: England
The Shell Grotto in Margate, Kent, was discovered in 1835 and has been open to the public since 1838. The subterranean chalk walls are a mind-bending mosaic of 4.6 million shells placed in the grotto by people of unknown origin.
Kartchner Caverns
> Location: Arizona, USA
Southern Arizona is home to the Kartchner Caverns, a large limestone cave system. The caves house the largest stalactite formation in the world.
Sudwala Caves
> Location: South Africa
The Sudwala Caves in Mpumalanga form one of the oldest cave systems in the world – possibly the oldest – dating back at least 240 million years. A large natural amphitheater inside the caves, dubbed Miriam Makeba Hall (in honor of the famed South African singer) has been used for concerts.
Luray Caverns
> Location: Virginia, USA
Luray Caverns, also known as Luray Cave, is the largest cavern system in the eastern United States. The cavern, in the Shenandoah Valley, has been open to the public since 1878. It is well-lit and the walkways are paved. The ceilings extend about 10 stories high.
Vilenica Cave
> Location: Slovenia
The Vilenica Cave in the Karst region of southwestern Slovenia might have been used as a shelter in ancient times, as artifacts have been discovered within. Tourists first visited as early as 1633, making this one of the oldest touring caves in Europe.
