Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

One of the most enjoyable bits of history at Coney Island and “the most romantic ride in the world.”

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

An 18-mile-long tunnel for sewage waste will soon wind within the bowels of Washington, D.C.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

The early data processor factory founded in Washington for the 1890 U.S. Census went on to become IBM.

Also known as the Founding Church of Scientology.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

100 years later, they're still down there.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

This forgotten boat elevator was an engineering marvel in its heyday.

Art deco landmark on the outskirts of Washington, D.C.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

A gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

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

A fantastic array of trays and cables once whisked books over to the Capitol at 600 feet per minute.

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

A clone of a cloned tree that was so important it allegedly had its own guards.

The most accurate timepiece in the world.

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.