This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

This small hilltop church weaves the urban history of Washington, D.C. with the national history of the United States.

An extensive, if one-sided, history of U.S. law enforcement's war on drugs.

Surrounded by traditional homes, this Tolkien-esque dwelling stands out on a quiet street in suburban Maryland.

The only place for a truly presidential dram.

Taste the white whiskey that the United States' first president once distilled and enjoyed.

Once a sewer culvert, this road tunnel now offers cyclists and pedestrians a subterranean stroll under the C&O Canal.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

A whopping 14,000 copper coins cover this miniature fighter jet.

Collecting 700 years of mechanical death-dealing, the NRA's sprawling gun museum is a revealing testament to the American obsession with armament.

Home to items never before seen by the public.

Perhaps the most scandalous statue of America's first president.

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

Coins and medals straight from the mint await visitors to this shop in the nation's capital.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

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

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

One of the last mosaic tile facades found in the city.

An Industrial Revolution-era public work that purified water using nothing but sand.

At 207 feet, one of the world's longest continuous escalators.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

The gravestone of the suffragist leader attracted extra visitors during the 2016 election.

High on a hill overlooking Los Angeles lives a world famous, high power conical Tesla Coil.