These natural hot springs form four-tiered soaking pools with temperatures ranging from 85 to 115 degrees Fahrenheit.

A crumbling hospital from the 1850s on Roosevelt Island.

A sculptural commentary on capitalism pokes up from the East River.

A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.

A little lighthouse in New York City, surrounded by mysterious stories of insanity-driven construction.

An art installation commemorates journalist Nellie Bly's undercover reporting inside a New York asylum.

With 3,000 bikes on display, the world's largest bicycle museum includes some famous rarities.

There aren't too many operational funiculars around, but Pittsburgh has two!

Rushing water plunges over a 100-foot drop created by an ancient lava flow at this majestic waterfall.

A haunted hot springs hotel that went from healing retreat to asylum before it was restored.

The wooden airship was the largest flying boat ever built.

Home of Howard Hughes' Spruce Goose.

A 36-ton remnant of the last Ice Age now resides amid picturesque vineyards.

This 85-foot-long table is made from a single slice of an old-growth Douglas Fir.

World's largest porcine hairball sits in a collection maintained by Benedictine monks.

A 19th-century architectural wonder designed by the "father of the skyscraper."

Buffalo's abandoned concrete grain elevators are getting a second life.

Stroll through a wonderland of stupendous moss-covered trees.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

Oregon's unexpected high desert, displaying layers of time in a colorful show.

No one knows how this Pacific Northwest spruce tree came to have so many trunks.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Only known mainland rookery of the threatened Stellar sea lion.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.