Witnessing the might of this dessert-colored desert waterfall is a rare, powerful treat.

An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.

Thousands of artifacts relating to human sexuality, including the world's largest sex bike.

Visit this playground of waterfalls, caves and sinkholes.

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.

An inconspicuous footbridge beloved by San Diego locals.

This free, take-a-book shop seems like a trick but isn't.

The highest bridge in America was built for an almost unnervingly small amount of money.

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

Rustic natural hot springs in the deciduous rain forest.

This lab's maddening silence is good for business but bad for sanity.

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

A whimsical village of unique treehouses resides in a Washington forest.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

These eerie outliers of the lightning bug family glow a mysterious blue color.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

A modernist landscape of water and sci-fi concrete.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

This naturally-sourced hot spring is now home to a clothing-optional resort.

Once a mortuary that held the remains of Buffalo Bill, this Denver hotspot is now a death-fixated restaurant.

Its buzzing collection honors vibrator history.

Home to items never before seen by the public.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.