The only castle in North America to ever house European sovereigns.

The "world's biggest dinosaur" once housed a creationist museum in its abdomen.

An emerald-green grotto just a short trip from Austin.

California's oldest wind harp represents a historic piece of America's Danish history.

The magic's in the hole!

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

The largest dune field in the Mojave offers a chance of hearing the 'singing sands.'

This 1967 experiment in modular architecture was designed to be a new model for urban living.

A black and white painted wall creates an optical illusion in the California desert.

The so-called "Bridge of Thighs" in Palm Springs allows nudists to discreetly cross the road.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

Home of the International Space Hall of Fame.

Once strictly off-limits, this lower level housing curious and priceless vehicles of the Petersen Automotive Museum is now open to the public.

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

Cave carved out of a huge snow drift collapsed killing one and injuring five in July 2015.

Portlandia is the second-largest copper repoussé statue in the United States.

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

66,000 pieces of art, donated by one of the world's richest men.

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

While these wooden totems bear a striking resemblance to First Nations artwork of British Columbia, their actual origins lay on the opposite side of the Pacific Ocean.

From mining complex to industrial exhibition, this museum once played a major part in the X-Files.

Remains of a Greek freighter trapped off of Rocky Point in 1961.