Northern Ireland's Brobdingnagian stepping stones.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

This man-made mound monument was built out of soil from all across the Polish empire.

The celebrity luchadores of La Paz are tough ladies in traditional petticoats and braids.

A marvel of Byzantine engineering under the streets of Istanbul.

The writing studio of an American adventure author, built in the style of a medieval castle.

An abandoned castle owned and ignored by Masons carries a cursed history.

A sculptor's dream castle turned fantastical ruin.

Bigfoot prints, Feejee mermaids, and haunted dolls on display in a tiny North Carolina town.

Continuing the tradition of the dime museum in style.

A former plague hospital turned medical museum.

Tucked behind the Institute of Neurological Science down a decrepit street resides the largest display of human brains in Latin America.

This collection started by a Cornell professor once held more than 600 human brain specimens, including the one that belonged to its founder.

This art center is way beyond your average pumpkin-carving operation.

From Japan to Italy, this California park explores the world's cultures through their gardens.

Over one million bird-related artifacts await.

A tunnel dug through the side of a mountain by hand provides convenient yet death-defying access to a small village in China.

The field of tiny caves that mark this Chinese cliffside are each their own historic Buddhist temple.

Caves full of Buddhist statues, incredible rock formations and a deserted lagoon.

A subterranean playground in an abandoned slate mine.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

Guests can stay at a hotel in the former French abbey where lie the tombs of King Henry II and King Richard the Lionheart.

The burning of this 12th-century church kicked off a campaign of Norwegian Black Metal terror.

Stay overnight in the world's most sleekly designed rabbit hole, free of charge.