The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

All that's left of the quintessential "cabin in the woods."

Enormous lake at the bottom of a unique cave system.

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

A cable-suspension footbridge that hangs high above the Mill River.

This path is named for a mythical half-boar, half-deer creature that once roamed the Green Mountains.

The world’s largest underground marble quarry is hiding in Vermont.

This cavernous abandoned marble mine is popular with ice skaters in the winter.

This semi-spooky remnant of an abandoned hotel provides fantastic views.

Ruins of the elaborate house where the enigmatic costume designer threw glamorous parties for New York's theatrical elite.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

An abandoned coal mine reached by a steep hike.

A 60-foot-tall tower provides unparalleled views of the southern Green Mountains.

The world's largest public collection of PEZ memorabilia.

Over 50 whirling pools left behind from the glacial age.

This evocatively named natural crevasse was created by a torrent of water that smashed right through a granite deposit.

It's not a typo, now say it five times fast!

A railway station takeout shop sells boxed meals in containers shaped like trains and snowmen that hold the country’s abundant regional delicacies.

The only thing sweeter than the potatoes is the canine proprietor of this roadside stall.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

A winding, blood-red tunnel of hardened lava navigable by foot.

This elegant arc of a waterfall marks a religious turning point.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

Medicinal spa created with the discharge from a geothermal energy plant.