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

Small monoliths of several varieties of stone sit alongside a wooded path in the Bronx.

This massive World War II calculator hearkens back to the days when "computer" was a job title.

This peaceful Massachusetts graveyard was one of the first "garden-style" cemeteries in America.

This parking garage was the site of what was - at the time - the largest cash robbery in history.

The site where Charles Dickens gave his first public reading of "A Christmas Carol" in the US.

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

A more than 260-year-old crypt built on Boston's oldest English burial ground.

19th-century operating theatre in which the use of ether was first demonstrated - plus, a skeleton and a mummy!

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

These enormous, stern-faced statues greet visitors with lanterns, and sometimes costumes.

An oft-overlooked, magically musical monolith that stands majestically between Arlington Cemetery and the Iwo Jima Memorial.

During the American Revolution, this mansion hosted failed peace talks between the British and Americans.

One of the most enjoyable bits of history at Coney Island and “the most romantic ride in the world.”

A crumbling hospital from the 1850s on Roosevelt Island.

An aptly-named street near the birthplace of the modern LGBT rights movement.

An ode to Japanese artist Hokusai, with a bit of a comical twist.

You can spend the night as an honorary lighthouse keeper in this quaint, historic beacon.

Step inside Lucy, the world's largest "elephant."

The longest-covered bridge in the state of Maryland.

One of the first intercontinental ballistic missile sites in the United States.

Dedicated to the history of the 1,000 nuclear missiles that once covered the Great Plains.

A six-ton, 12-foot-tall concrete prairie dog is touted as the largest in the world.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.