A historic observatory precariously perched at the "Top of Europe."

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

The first geometric self-supporting spiral stairs in Britain are a truly beautiful sight.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

At high tide this strange footbridge appears to have no purpose whatsoever.

Blue-green pools and smooth stones comprise one of Spain’s most idyllic hidden wonders.

The ruins of a medieval castle that once belonged to one of the most powerful families in the Netherlands.

This grassy, tree-lined hill shares a name with the much-loved novel that it inspired.

Rainbow-hued in the summer and crystalline in the winter, this salty lake has inspired battles, temples, and plenty of awe.

The platform atop this verdant volcano was built with the help of a royal elephant.

This legendary urban waterfall creates a dazzling display of rainbows.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

The hill that gave the Massachusett tribe, and later the state, its name.

A boardwalk winds through this sliver of coastal nature hidden within Sydney.

Volcanic rocks ground down into sand make this Spanish beach as black as night.

You can row a boat through this ancient underground reservoir.

Elevated freight railway turned wildly successful urban park.

This Parisian café sticks almost exclusively to an ethos of reuse.

Rare recess caves fill this unbelievably beautiful Ohio park.

A serene temple with stunning stained glass hides in downtown Dallas.

An out-of-place grove of sequoias thrives in northern Spain.