Holy Hindu shrine in an enormous, monkey-filled limestone cavern.

Lavish royal estate punctuated with heated greenhouses.

What was once a trend-setting, phrase-coining icon of architectural splendor is now a rotting, forgotten hulk.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

Beyond the usual stories that attend old prisons, this one has deep bloody undercurrents.

Between Neo-Pagans and Neo-Nazis, these strange rock formations have a curious cult following and a very strange history.

The longest navigable underground river in the United States is home to countless blind and albino animals.

An underwater restaurant, surrounded by a coral reef.

The only Bahá'í house of worship in North America and one of only a handful worldwide.

A hyper-luxurious, 12,000- square foot home might be buried beneath Queens, still waiting to protect you from nuclear missiles.

The crumbling remains of a 19th century fortess.

Caves famous for the dragon-slaying saint who lived there.

A walkable map of the world, made from soil and stone by one man.

A 18th century graveyard and its astonishing cortege of macabre iconography.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This everlasting lightning storm may be the world's largest generator of ozone.

In this century-old literary safehouse, print is alive and well.

An offbeat angle on the ocean viewed through an antiquated lens.

An intricate and amazing house built by architect Karl Junker.

Reclaimed by nature, the ruins of Doodletown, New York are remnants of a town consumed by a state park.

Human-made caves excavated to hide a secret society of wealthy pagans.

Dictionary Johnson’s favorite feline.

The highest dunes in California are the most likely place in the area to hear the Singing Sands.

Steaming blood-red hot spring from hell.