San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Depicting scenes of everyday life - and specific individuals - in Great Depression era San Francisco.

A tribute to one granddaughter's old apartment which now represents the whims of each visitor.

World's second largest particle accelerator, where nature reveals its secrets.

Arguably the best example of an authentic Dutch windmill in the United States, rivaling its counterparts in the Netherlands.

An exhibit of items from the mental institution where Mary Todd Lincoln lived after her son conspired to have her committed.

How did the 110-foot limestone statue cross the road?

"World's largest scrap metal sculpture" stands in an outdoor sculpture garden in the middle of Wisconsin.

A bizarre house filled with an astounding array of collections.

To truly appreciate Detroit's landmark skyscraper, you have to step inside.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

These enduring murals depicting a distinctly Marxist tribute to capitalism could not even be defeated by McCarthyism.

Four, 18-foot-tall badminton shuttlecocks lie scattered about the lawn of a Kansas City museum.

A remarkably opulent mansion with a tragic history.

This otherworldly church spire reaches up toward the heavens.

This mansion was made famous by its colorful cast of owners and location along the Sante Fe Trail.

These elevated trucks were put in place as a middle finger to The Man, but are now considered folk art.

Community bookshelf of 25-foot-tall book spines.

Two hundred tons of pioneer artifacts were painstakingly recovered from a shipwreck at the bottom of the Missouri River.