The school tested mustard gas for the U.S. Army during World War I.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

This leafy estate is worth $18 million and is so grand it has two mailing addresses.

The walls of the iconic dome are hollow and have a secret stairway.

A wondrous old library overlooking the nation's capital.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

The United States Capitol's former columns still stand.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

A sprawling Victorian farm that has been surrounded by a capital city is one of Canada's greatest treasures.

A quarter mile off the coastal tip of Maine you'll find the "Beloved Island" of Franklin Delano Roosevelt.

A mysterious lake provides fresh water without any source, somehow restoring itself from atop its mountaintop perch.

Go inside the house that inspired L. M. Montgomery to create one of literature's most beloved heroines.

Rusty red sands line the shores of this Canadian Province.

A high point in Vancouver kitsch.

A neutrino detector built into the largest man-made underground cavity in the world.

This conservatory allows a little bit of the tropics to thrive in the middle of a major Canadian city.

One of Canada's oldest museums, the beautiful Redpath has been serving up Natural History and Ethnography since 1882.

Live long and prosper in Vulcan, Alberta.