Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

Commonly acknowledged as the only public monument to the Devil himself.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

An eclectic collection of thousands of items owned by the sculptor Frederic Marès.

A beautiful but toxic fountain of mercury.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

Dramatic river bend surrounds a natural red-rocked pedestal.

A crumbling hospital from the 1850s on Roosevelt Island.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

Water and windows define this defensive Italian well.

These free-roaming horses were once destined to disappear from the land.

A spiritual vortex among the red rocks in Sedona.

An urban laboratory.

See massive fossils that are over 200 million years old in northeastern Arizona.

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

A reproduction of earth's many biomes.

The first permanent memorial to a unique secret weapon of World War II.

Charleston's historic city jail once held everyone from pirates to Civil War POWs.