The rocks in this arid basin leave trails of movement behind them.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

This cave holds a surprisingly colorful variety of geological oddities.

The city of Rockford, Illinois is symbolically protected by a quartet of fittingly stony sentinels.

Shop of curiosities with a dinosaur museum tucked in its basement.

Half-sized replica of the Leaning Tower of Pisa built to honor Galileo.

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

The face of a woman pushes its way through the earth.

Robots, lasers, and whoopee cushions, oh my!

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

One of the first historical sites of an alternative universe was installed in the town of Paris, Illinois—which is now home to an annual spelling bee of Kcymaerxthaereal words.

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

Once adorning a New York skyscraper, these reclaimed ruins now haunt an Indiana park.

This small road tunnel is the only place where you can cross beneath the Erie Canal.

Ruins of a once-prized railroad station in New York.

A book collector's dream, this Toronto bookstore has the world's first "Biblio-Mat," a random book vending machine.

The oldest landmark of Toronto is a testament to shifting sands.

This massive, ancient stone was disassembled and then put back together again.

One of the largest underground systems runs under Canada's largest urban center.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

Wondrous sandstone hoodoos where Native Americans collected clay for pottery, 9,000 years ago.

A place where the laws of nature seem to have gone completely berserk... but of course haven't.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

The World's Largest Bull.