Earth's tallest volcano is sacred to Native Hawaiians, and home to a dozen world-class observatories.

A priest with no formal artistic training used basic house paint to create gorgeous religious scenes inside this historic church.

This local gem houses the largest collection of pre-Raphaelite paintings outside of the U.K.

It is said the legendary wizard once lived in this sea cave beneath Tintagel Castle.

Make a wish at what might be America's only Catholic shrine to a sinner.

Hidden inside this Arizona fast food franchise is an in-depth exhibit on the famed WWII counterintelligence program.

Hike the unusual hoodoos and rock formations that form this little-known natural wonder.

Founded by members of the Tohono O’odham Nation, this one-room joint's James Beard–winning fry bread is light as a cloud.

One of the U.S. Forest Service's only mansions is outfitted with a dinner table for floating food.

The Pennsylvania landscape depicted by a quarter mile of mosaics made from used road signs.

The universally beloved children's television figure is interred on a high hilltop in one of western Pennsylvania's oldest cemeteries.

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

This cemetery features modernist statues as strange as its name.

A serene temple with stunning stained glass hides in downtown Dallas.

The last occupied troglodyte dwellings in England weren't abandoned until the 1960s.

Home to a vast and influential collection of Shakespeareana.

A wondrous old library overlooking the nation's capital.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

It was once the base for a series of domestic terror attacks.

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

This meticulously extracted nervous system allegedly came from a 19th-century custodian who donated her body to science.