The notorious headquarters of a corrupt political machine.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

Golden Gate Park's historic collection of plants.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.

Olfactory delights in San Francisco's Botanical Gardens.

The largest underground pedestrian tunnel system in the U.S. mostly caters to the people working in the offices above, but provides a great, air-conditioned way to traverse the city.

Frida Kahlo's childhood home, now a museum of her life and works.

This stunning concert hall has become a symbol of Iceland's national recovery.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Medicinal spa created with the discharge from a geothermal energy plant.

Four-story concrete hotel never opened to customers.

The king of U.S. high points towers over every other peak on the continent.

Siberian husky that delivered a life-saving antitoxin.

Considered by many to be one of the most dangerous highways in Alaska.

While not recognized by Guinness, this chocolate waterfall is likely to be the world's largest.

An exotic wildlife habitat right off The Strip.

One of the world's tallest Ferris wheels takes visitors high above Las Vegas in a spinning party room.

Once the site of a Native American harvest festival, this humble clearing later played an invaluable role in the birth of jazz.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

Inside houses a vast collection of military aircraft and missiles spanning the ages.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.