In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

The artist James Turrell is repurposing an extinct volcano crater as an observatory to experience the cosmos.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

See massive fossils that are over 200 million years old in northeastern Arizona.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

Dramatic river bend surrounds a natural red-rocked pedestal.

Most-visited and most-photographed slot canyon in the American Southwest.

Rippling sand dunes frozen in the Arizona rock.

This seaside sanctuary was once one of the most important religious sites for women in ancient Greece.

Built by the Ancient Greeks, this chariot bridge is still in use today.

According to legend, this cavern holds the passage that Persephone used to travel to and from the underworld.

Every spring, locals see the shadowy figures of a ghost army of slain Greek soldiers descend upon this ruined fort.

A small island with shimmering pink sands, home to loggerhead turtles and rare plants.

The rocky remains of an ancient Greek forest.

Ruins of a 13th-century fortress perched above a breathtaking Mediterranean bay.

A little-known park with unusual, half-ruined structures and a mystical energy.

One of the largest single-span stone-arch bridges in the Balkans looks like something straight out of a fairytale.

Temple complex that once housed the famous statue of Nike.

The oldest olive tree in Greece has been bearing fruit for at least 2,000 years.