A memorial to the tens of thousands of Irish who fled to North America during the Great Famine.

The oldest landmark of Toronto is a testament to shifting sands.

An auroral research program that superheats the ionosphere.

Open day and night, a church with three pews and Bibles.

A massive, heart-shaped, wind-carved crater in the middle of the Israeli desert.

The maze-like transportation hub contains abandoned areas, derelict stores, and a resident bat colony.

A modern-day cabinet of curiosities housed in a 300-year-old inn.

Where the U.S. government kept its actual treasure, before Fort Knox.

The "lovely red Vega" of the legendary record-settling pilot.

Decades before the scandal, this staircase on the river was a literal "water gate."

The most accurate timepiece in the world.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

The oldest continuously operating fish market in the United States.

The national park was once a plantation estate.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

Largest Roman Catholic church in North America.

The most decorated dog of World War I is preserved in the Smithsonian.

There’s a hidden military meme engraved on the World War II Memorial.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.