World's first "penitentiary," meant to be humane, drove men insane.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

Giftshop catering to cryptozoologists and anyone with a sense of humor.

An astounding collection of medical specimens, including bits of President Lincoln.

Nine of the very few concrete ships ever made in the U.S. are beautifully decaying off a Virginia pier.

"Not too many people can say they've had a nuclear bomb dropped on them, not too many would want to." — Walter Gregg.

Welcome to old Florida, where a 1940s mermaid show is still enchanting visitors.

Florida castle built with aluminum printing plates.

Manatees congregate around a power plant's discharge canal where the water is especially warm.

Museum dedicated to "the man who moved the Earth."

A 20th-century picture show in 3-D.

An underground city of salt.

Hidden beneath the streets of London is a secret subway that only carried mail.

The first archaeological site discovered by aerial photography.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Behemoth, cannon-like telescope operated by generations of Irish earls.

Northern Ireland's Brobdingnagian stepping stones.

An antique curios dealer and hybrid taxidermist.

Grottoes, sculptures, and recycled ceramics permeate what was once just a small farm in France.