To find the "unicorns of the deep" you've got to go downstairs.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

This chapel on a cliff is renowned for its healing powers and was founded on the site of a supposed divine intervention.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

This one-time health resort was used by aristocrats around the world.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

When a supermarket opened up shop within a medieval building it became protected by UNESCO on a technicality.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

This chilly Canadian hotel has a four-month lifespan due to the unusual material it's made of.

The larger of two volcanic peaks rising out of the crystalline waters of the Caribbean.

The remnants of an abandoned, 19th-century gold mill along Aruba's rugged northeastern coast.

A safe place for the wild donkeys of a hot vacation destination.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

The magic's in the hole!

A massive sea stack famous for its appearance in The Goonies.

A trash dump made beautiful by nature's power.

A man-made island in scenic San Francisco Bay.

This private residence was the template for one of the most beloved television homes of all time.

Don't blink or you'll miss it.

A tribute to the statues of Easter Island along Route 66.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

The unusual patterns in this rock formation result from two distinct modes of weathering.

A tunnel with windows, so you don't miss out on the impressive views.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."