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

This leafy estate is worth $18 million and is so grand it has two mailing addresses.

A Spiritualist house of worship where believers communicate with the dead in the spirit world.

A nostalgic bibliographic gem.

Largest Roman Catholic church in North America.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

This grand gothic brewery has been pumping out suds for over a hundred years.

Home to items never before seen by the public.

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

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

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

The United States Capitol's former columns still stand.

San Francisco’s condensed garden of incredible plant growth.

A century and a half of research in the sciences and natural history, still going strong.

A classic advertising icon immortalized in regal bronze.

One time home to turn of the century explosives, now hidden under the Bay Bridge.

Shoot for par over the bodies of the dead on this cemetery-cum-golf course.

An enormous artwork that colorfully celebrates over 150 years of US military achievements.

Once the fastest ship from San Francisco to Tahiti, the Galilee now lays in pieces in three different cities.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

A miniature view of the park, caught in time.