Carlsbad Caverns - New Mexico

Carlsbad Cavern is one of over 300 limestone caves in a
fossil reef laid down by an inland sea 250 to 280 million
years ago. Twelve to fourteen thousand years ago,
American Indians lived in the Guadalupe Mountains;
some of their cooking ring sites and pictographs have
been found within the present day boundaries of the cave.
In 1923 Carlsbad Cavern was proclaimed a national monument.
Through illustrated articles published in magazines such as
National Geographic and by word of mouth, Carlsbad Cavern
became one of the world's most celebrated caves.