Few other hotels can rival the grandeur of the Castle in the Rockies.

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

The site of Paul Revere's historic two lantern warning.

The first American department store, and home to the largest operating musical instrument in the world.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

These faux-cliff dwellings allow visitors to climb around on a replica archaeological site.

This cave holds a surprisingly colorful variety of geological oddities.

Despite being one of the most photographed vistas in the Rockies these twin peaks are rightfully known as the "Deadly Bells."

The 340-year-old house that inspired the classic Nathaniel Hawthorne novel.

This Colorado hiking trail provides a small gold mine of abandoned gold mines.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

The crumbling remains of a 19th century fortess.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

Architectural monsters are devouring this palace's every door and window.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

The world's longest known cave system.

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

A beautiful geyser under environmental threat.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

The first declared National Monument in the United States.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

Paranormal experiences in this hotel's room 217 led Stephen King to write "The Shining."

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