A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

Nine caves filled with recently-discovered archaeological finds under the houses and the streets of the most ancient district of an old town.

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

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

A white oak with property rights.

This North Carolina museum is keeping the pinball craze alive, with a little Space Invaders on the side.

An idyllic mineral hot springs facility with a more-than checkered past.

North Carolina's finest examples of Native American pictographs have survived for 5,000 years.

A mountaintop space observatory that is certified dark.

An overgrown collection of miniature buildings still stand as evidence of one couple's obsession with The King.

Two thousand artifacts from around the world collected by one woman who loved to travel.

An eccentric home in Sicily turns heads on a regular basis.

Knoxville’s architectural icon was the symbol of the 1982 World’s Fair, even catching the googly eye of Bart Simpson.

One street divides a single town that stands in two U.S. states.

Amazing pre-Civil War ruins alongside a shallow, rocky river that hosts beautiful (but endangered) lilies.

One man's extraordinary topiary garden in a small South Carolina town.

The uniquely-designed winter home and sculpture studio of Anna and Archer Huntington.

This woodland architectural installation acts as a camera obscura for the heavens.

A historic covered bridge, only one of two remaining in North Carolina.