Home to items never before seen by the public.

The national park was once a plantation estate.

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

The site of the climactic scene from the classic horror film is now a historic landmark.

The word "Watergate" will forever be associated with the infamous scandal in 1972, but this fountain is famous in its own right.

The hippo that stands on this university campus was once a drunken flea market purchase.

Also known as the Founding Church of Scientology.

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

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

A tribute to the beloved, kind-hearted "homeless mayor" of Silver Spring.

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

These five Art Deco homes were meant to solve the "small house problem."

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

Cold War intelligence agents monitored communist embassies from an attic in a former pigeon coop.

Hidden within an idyllic suburban garden is a memorial dedicated to the victims of a terrifying spree of killings committed on U.S. soil.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

A jaw-dropping "megalibrary" that turns book-browsing into a geometric adventure.

Gilded heaven for philatelists and architecture freaks, still in full working order despite sitting atop tremulous ground.

Mexico City's largest market contains a Willy Wonka-esque wonderland.

CDMX's home for the world's culinary delights.

Many people don't realize there’s a lot going on in—and below—the world’s tallest triumphal arch.

This "City of Books" holds a museum, library, and the complete personal book collections of five of Mexico's greatest thinkers.

This neon installation is a tribute to a Mexica god, who gave his skin to humanity.

In Chapultepec Park there is a pavilion gifted to Mexico from South Korea to honor the 1968 Summer Olympics.