After a short-lived attempt to bring America in line with the rest of the world, this road was left in metric.

An off-the-beaten path cave with an underground lake.

A reproduction of earth's many biomes.

Legend says train robbers stashed their gold within the depths of this unusual cave.

America's only nuclear missile silo open to the public.

During World War II this was the site of an "honor camp" used as a prison for draft dodgers, Native American conscientious objectors, and Japanese-Americans—including a man who brought his case against the camp to the Supreme Court.

The remains of this rugged homestead ranch offer a brief glimpse into a bygone era.

Miniature art that tells an enormous story.

A statue honoring 44 continuous years of greeting passing ships.

This kitschy tavern is also home to rare early editions of "Treasure Island."

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

The grotto where Saint Ignatius of Loyola lived as a hermit for nearly a year.