These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

A bizarre house filled with an astounding array of collections.

House built with over 60,000 glass bottles.

Strange physical sensations and optical contradictions keep visitors coming back for more.

A wacky two-story folk-art assemblage of carved and found objects, with lights, motion, and sound now in need of financial support.

Hell on Earth is actually a small town in Michigan where anyone can be mayor for a day.

A precariously balanced rock perches on the edge of a cliff created tens of thousands of years ago by glacial erosion.

A giant telephone commemorates the last "crank" call ever made in the U.S.

Turns out you can see the world without ever leaving Maine.

The highest point in Maine is a grand gift to the state citizens that also happens to be one end of the Appalachian Trail.

Toy museum in a former tavern is the expression of one man's life pursuit of the aesthetic power of cartoon imagery.

The world's largest rotating world.

Three courses accompanied by Christian rock.

This boulder stays on its mountain thanks to a huge chain and on the map due to local legend.

An enormous natural sandstone bridge in Kentucky.

The world's longest known cave system.

The United States's largest hand-dug well is topped with a state-of-the-art museum.

Massive still life just off the highway in Kansas.

A unique attraction and museum dedicated to exploring iconic roadside structures.

The evolution of recreational vehicles and motorhomes is on display in the “RV capital of the world."

Display that gathers the basic elements of the universe in one convenient location.

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

Known as the "Cross At The Crossroads," this massive metal cross is just short enough to avoid the FAA.

A 30-foot man on a penny-farthing bicycle rides along the banks of the Mississippi.