A landmark for a trailblazer for female architects and the designer of one of the most famous and opulent buildings in California.

The decor of this Hollywood movie palace just barely predated the opening of King Tut's tomb.

This quirky UFO-shaped curiosity is often mistaken for the airport’s control tower.

This forgotten Frank Lloyd Wright house is an architectural marvel at the end of a sleepy residential street.

An expansive book store, art gallery, and curio shop with wares ranging from tarot cards to novelty socks.

Hidden above a drug store on a nondescript corner of Lincoln Heights is a private clubhouse for intrepid explorers.

Beautiful Victorian buildings from L.A.'s forgotten architectural past.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

Scores of vintage street lamps shine along L.A.’s Miracle Mile.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

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

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

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.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

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

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

A nostalgic bibliographic gem.

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

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

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

A historic neighborhood church is reborn as a psychedelic arts collective.

Home to items never before seen by the public.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.