The world's first combination ski slope and power plant.

This striking royal residence is the largest Renaissance-style castle in Scandinavia.

This Denmark theme park is part family attraction, part experimental archaeology project.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Color-coded signs direct drivers on a network of routes designed to avoid Pittsburgh traffic.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

There aren't too many operational funiculars around, but Pittsburgh has two!

The only way to see Pittsburgh is from the top of this lookout point, just like the ancient members of the native peoples did.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

Found art has transformed this Pittsburgh neighborhood into a psychedelic dream.

On the grounds of a hospital in Ghana, a legendary sword said to have been plunged into the earth hundreds of years ago.

An enormous public square and parade ground built to celebrate Ghana's independence.

Where thousands of slaves passed through the "Door of No Return."

For centuries, Jeddah’s old town was a major trading port and a point of entry for Hajj pilgrims traveling by sea.

The rocks around this mountain are filled with so many carvings that the area became known as the "open library."

In the middle of a barren desert, a massive, solitary rocky thumb juts out.

The oldest surviving one-room schoolhouse in Montgomery County, Maryland.

The smallest covered bridge in Maryland.

Although built to generate electricity for Marylanders, this dam has become an all-you-can-eat buffet for American bald eagles.

The 72-foot giant escaped confinement in a large patch of mulch only to be reburied in the sandy shores of the Potomac River.

Once a thriving business district, this former shopping area is now an urban ghost town in the heart of the city.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.