The oldest private residence in New York City.

This narrow coastline trail through the dense Kauai wilderness is among the most beautiful and dangerous in the world.

A once-glowing grotto at the bottom of Waikapalae Wet Cave.

Now a pedestrian bridge, this was once part of a narrow-gauge railroad that ran along the east coast of Kauai.

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

This ruined fort and statue are a testament to the last king of Kaua‘i’s savvy diplomacy skills, which briefly brought Russians to Hawai‘i.

Gold Rush-era tombstones line the park's paths.

Visible below the waves are memorials to the city's Gold Rush dead.

This restaurant features Native American foods from across the country.

A massive ultra-modern church presents a science-fiction view of Catholicism's inclusive future.

A restored 1920s cascade stairway provides one of the best views of Oakland's Lake Merritt.

Bonsai garden in Oakland is curated by the first non-Japanese female bonsai master in the United States.

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

Early prototype for Frank Lloyd Wright's Guggenheim.

This teeny-tiny park built by a San Francisco man in 1962 is mostly stairs.

This church on a Tohono O'Odham reservation has stood since 1797.

The highest natural point in New York City and all of the Atlantic coastal plain.

A once-groundbreaking power plant turned into a hotel and mini-museum of archeological and geological wonders.

This hidden treasure provides a charming access point along the south side of Baker Park.

This house was the subject of an Edward Hopper painting, which in turn helped inspire the design of the Bates house in Alfred Hitchcock's 'Psycho.'

A fire lookout atop a glacial pinnacle is reached by climbing three vertiginous flights of stairs.

The longest covered bridge in Delaware.

Craggy concrete faces are hidden in the walls of this artificial cave along the San Antonio River.

Legend has it the commander of the defenders drew a fateful line in the dirt with his sword just before the final battle.