In this historic region, homes and churches are carved into ancient volcanic rock formations.

You can row a boat through this ancient underground reservoir.

A cemetery housing wild west legends in South Dakota.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

A spooky defunct railroad tunnel now part of a sprawling trail.

Journey through the largest remaining peat bogs in the contiguous United States to see the wilderness as it once was.

Terraced flowerbeds and rock sculptures in the midst of the Minnesota wilderness.

Minnesota's highest point is a scenic vista marked by a plaque and armies of mosquitoes.

Duluth mineral magnates built this charming art deco lodge to be their private clubhouse.

The home where a lovestruck Fitzgerald wrote his first published novel, "This Side of Paradise."

14th century Norse artifacts in Northwestern Minnesota could have proved a Viking landing before Columbus.

A quaint Russian village in the middle of a German metropolis.

Explore the complex ecology of this multifaceted nature preserve by riverboat.

This historic stone bridge has an entire neighborhood clinging to its sides.

Ruins of a German Castle on top of a towering stone pillar.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

Golden cobblestones remember a time when this small alley was used to avoid having to give a Nazi salute.

These bronze pamphlets remember a remarkable group of Germans who fearlessly opposed the Nazis in the very center of their power.

The medieval network of canals hidden underneath the city is opened to explorers each year.

Gladiators battle and chariots race daily in the ruins of a once-great Roman city.