The massive, original Colgate Clock is mounted on a defunct factory building that was once a prison.

Deep scars on the earth left by the Ice Age.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

This ancient sinkhole-turned-healing-pool is a treasure trove of archeological discoveries and may even be the Fountain of Youth.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Every equinox this Maya pyramid puts on a spooky ancient light show.

A spiritual vortex among the red rocks in Sedona.

Allowing humans and fish alike to migrate from freshwater to saltwater and back again.

A museum dedicated to the history and exploration of both popular music and science fiction.

A self-built castle made by a mysterious man.

A toweringly silly piece of modern art has been delighting locals since the 1980s.

The only arched bridge made of stone on the entire Mississippi River.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

The legacy of an unsolved, gruesome murder rests beneath the spans of this historic bridge.

The world's tallest doric column is this Ohio monument to a naval victory in the War of 1812.

The fifth-longest suspension bridge the world, connecting one Michigan peninsula to another.

This urban drawbridge gained eternal pop culture fame when the Blues Brothers jumped it while it was raised.

A place to eat for on-the-run agents and espionage enthusiasts.

Giant six-pack could provide one person a six-pack a day for 3,351 years.

For just a few bucks, this Iowa funicular will let you feel like an 1800s fat cat.

These pretty kitties killed and ate as many as 135 railway workers.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

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

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