This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

Believed to be the birthplace of the United States Marine Corps.

An Irish Memorial commemorating those who perished due to potato blight.

Medieval streets buried beneath a papal fortress now form an underground city you can walk through.

Frida Kahlo's childhood home, now a museum of her life and works.

In Coyoacán, a pair of coyotes crown a public fountain in reference to the ancient Aztec name of the borough.

One of the city's few vendors selling the Sierra Norte's ancestral beverage lies within a hidden farmers market.

This huge pile of volcanic boulders hides a stunning network of secret grottoes.

A room in New York City that contains 250 cubic yards of dirt.

One kilometer of thick brass rod laid out before your eyes.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

The historic home still shows the scars from a little run-in with the British in 1813.

A museum dedicated to exhibiting remarkable outsider art.

A 200-year-old bar with a cheeky name claims to have served Edgar Allan Poe his final drink.

A collection of artifacts from Maryland's maritime past.

Scary stories haunt this wooden bridge.

This English-inspired Maryland garden is home to acres of opulent plant life including bushes shaped into an entire fox hunt.

An outlandish shoe shaped house built by an eccentric millionaire.

An industrial waste tourist attraction.

These unique rock formations were created during the Ice Age.

On the outskirts of Pennsylvania’s capital city, a reminder of the worst accident in U.S. commercial nuclear power plant history.

The slate extracted from these Pennsylvania quarries was once hailed as the finest in the world.

Although built to generate electricity for Marylanders, this dam has become an all-you-can-eat buffet for American bald eagles.

Don't get it twisted: This is the oldest pretzel bakery in the United States.