An abandoned 1970s theme park that has been turned into a space for waterfront walking.

The Catskills retreat of naturalist writer John Burroughs.

A modern addition to the Greenpoint skyline.

Nature and beauty amidst pollution and industrial wreckage.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

A planet-hunting astrograph built in the 1920s to seek out the so-called "Planet X" beyond Uranus.

A spiritual vortex among the red rocks in Sedona.

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

Only hotel where you can legally launder money.

Adolph Sutro's little-known, geographically inaccurate, deprecated monument.

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

Two thousand artifacts from around the world collected by one woman who loved to travel.

The Wright Tavern is possibly the most important building in Concord Massachusetts to the American Revolution.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

Built in 1821 using rooms from another estate, the Phillips House is the only historic home on scenic Chestnut Street open to the public.

A burial ground for workers at one of Hawai'i's largest sugarcane producers that laid buried for decades.

This monument built by Japanese American immigrants spent decades underground.

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

Hawai'i's oldest wooden house was shipped around Cape Horn from Boston in 1820.

The oldest continuously-operated inn in the United States, once owned by Henry Ford.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

The very first subway station in New York City is beautiful, decked out in chandeliers, and ... abandoned?

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

A former steam-powered mill from the 1800s is now an industrial park with a giant steel dragon slide.