Behind medieval walls in a corner of bustling Palermo is a breathtaking former mosque once inhabited by a wolf-taming hermit.

You feel like you're in a forest, but you're actually walking amidst the branches and trunks of a single giant tree.

The tech giant built three enormous glass orbs in Seattle so employees could work inside a rainforest greenhouse.

The world's most active stratovolcano is almost always erupting.

Dedicated to the 4th Baronet of Sledmere.

This rest area is also home to a remarkable petroglyph site.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

A clear blue swimming hole with hidden caves, still unexplored.

In Florida, these naughty monkeys live on their own mini-monkey Alcatraz.

Once an ancient sea, this landscape of rocky ravines is filled with the fossils of ancient marine life.

More than 350 million years ago, western New York was covered in a vast sea. Today, you can dig up the remains of the plants and animals that lived there.

The flow from this waterfall sometimes comes out of springs below its rim.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

These narrow stone granaries have been used to store and dry out grain for hundreds of years.

This mid-19th-century dugout was once home to a Swedish family as they erected their homestead.

This scalding hot river was thought to be a myth until one geoscientist made it his quest to study the mystical waters.

This long-distance walking route follows the Prime Meridian line as it passes through England.

This trail leads to a mine that was used as a sanctuary during the Great Fire of 1910.

A trail weaves through the verses of a poem illustrated by stone sculptures inspired by Native American pictographs.

The illuminated falls are a gem in North Cascades National Park.

An American city stranded at the tip of a Canadian peninsula where strict adherence to the "49th parallel rule" became problematic.

One small town in the Pacific Northwest transformed itself into a Bavarian-themed tourist destination.

Hundreds of drawings left by the land's previous inhabitants remain mysterious.

One of the American Southwest's most extensive collections of Navajo rock art.