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

The magic's in the hole!

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

The only surviving prototype for Buckminster Fuller's house of the future.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

An old slaughterhouse now holds the largest collection of pig artifacts.

The last bastion of Roman presence north of the Alps looms over a German town.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

Birthplace of the "Cat in the Cradle" and a cluster of iconic, original windmills that let the Dutch tame the seas.

There has been an astronomical clock on this spot since the 14th century.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

This stoic, if derpy, giant stands as a monument to Oregon's statehood and the novelty culture of yesteryear.

A spiritual vortex among the red rocks in Sedona.

For just a few bucks, this Iowa funicular will let you feel like an 1800s fat cat.

At 135 years old and counting, this historic print shop is heaven for poster nerds and music buffs.

This replica of the Greek structure is in the heart of Nashville.

The world's longest outdoor covered escalator system transports commuters through Hong Kong's hilly terrain.

Come for the flowers, stay for the bats!

A New Zealand communications tower stands as the tallest structure in the Southern Hemisphere.

Major tourist destination known for its bubbling mud-pools and hot thermal springs.

After the devastating 2011 earthquake, historic Christchurch begins to recover, starting with the pop-up Re:START mall.

A glacier pocked with ice caves and surrounded by rainforests.

Dolphins, ancient clams and hundreds of waterfalls make this one of the world's top tourist destinations.

A giant Troll lurks under one of Seattle's oldest bridges.