One of the oldest show caves in Arkansas.

No one messes with the Massachusetts sacred cod, not this time...

This was once the largest four-sided clock in the world (yes, even bigger than Big Ben).

The first home and studio that belonged to the famous architect.

Dedicated to a colonial woman who was hanged for being a Quaker.

A dedication plaque on this Boston tunnel is a microcosm of a massive, controversy-laden construction project.

A Route 66 filling station that was designed to resemble the Hagia Sophia, and is now the symbol of an arts district.

A journey begins with a single step, and for many, the road-trip of a lifetime started at this Chicago intersection.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

A historic ballroom host to famous performers from the big band era to 1980s rock.

These dramatic cola-colored falls have appeared in a poem by Henry Wadsworth Longfellow and a song by Sufjan Stevens.

The final resting place of the world's first nuclear reactor.

Kwanu'sila the Thunderbird has been silently watching over Chicago for more than 100 years (kind of).

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

How did a 2,000-year-old Roman column find its way to a Chicago park?

The artwork commemorates the many ways 20th-century people perished while on the clock.

Known as "Toronto's Flatiron."

This whimsical fountain pays tribute to Toronto's four-legged friends.

The National Park Service’s best-kept secret with views that rival any in D.C.

See where Bill Murray kidnapped a hapless Punxsutawney Phil.

More than 7,000 gallons of water pour over these cascading red quartzite waterfalls every second.

Once designed as the entrance to Buckingham Palace, this structure was later relocated and stands as a victory arch.

After this historic church was destroyed by World War II bombing, its blackened shell was left standing as a monument.

Vermont's hills are alive with the sound of music at this historic hotel.