Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

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

This black shoreline is made up of exploded lava particles.

A beach made of semi-precious green sand on the Big Island of Hawai'i.

Climbing this abandoned railway leads to breathtaking vistas of O‘ahu.

This unusual lava tube spouts seawater during high surf.

Try your hand at old-fashioned coffee growing at this museum devoted to one of the world's most coveted beans.

This former luxury resort in Kaua'i is now an abandoned relic.

A community-run museum invites visitors to explore Jewish communities before and after the Holocaust.

This tiny little island has, as the name says, just enough room for its single house.

This unassuming layer of clay boasts an out-of-this-world origin story.

A cooled lava flow from the Haleakalā volcano formed these surreal-looking columnar basalt structures.

From working out of his garage to the James Beard semifinals, one Tucson baker has kept his fan base—and his grains—local.

Eight huge lanterns lining a city street can change color on command.

Anyone can control this glittery light installation with just a phone call.

A sparse, solitary sequoia still stands as a living tribute to the famous conservationist who planted it—but it's dying.

This eagle-topped spire remembers the military commander who snatched up California for the United States.

This restaurant's marvelous musical machines include a self-playing violin.

A mysterious monument covered in a binary code marks the heart of tech.

Radioactivity still cause for concern at this urban explorer's paradise.

Once America’s most beautiful army base, this abandoned military fort on the coast of Monterey Bay has been left to the elements.

A regular looking rock with an unbelievable history.

The world's first permanently occupied mountain-top observatory continues to report on the stars.