The only road through the heart of Glacier National Park.

Home to the deepest rift anywhere on Earth.

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

The longest living non-clonal organisms on Earth.

Despite its name, this route in southern Utah offers a heavenly day trip.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

Erosion and various mineral deposits give this striking canyon its distinct color and soft appearance.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

This public square capitalized on a single Eagles reference to bring some life back to an Arizona town.

Visitors can walk over the largest concentration of Columbian mammoths to have died from one event.

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

This 41,000-acre wetland complex is the largest marsh in the interior of the United States.

When you visit his grave, be sure to rub the Great Emancipator's nose for good luck.

The author of Uncle Tom's Cabin was neighbors with Mark Twain while living in this Connecticut home.

The former home of Samuel Clemens and family remembers the happiest period of the author's life.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

Oldest synagogue in the United States.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

An interesting decoration on this historic site, this weathervane comes with as many legends as it does questions.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

"A hideous albatross in the Hudson River Valley."

The highest point in the state of New Hampshire, and while unlikely "the worst weather in the world," it sure seems that way to hikers.