The world's largest solar furnace uses 10,000 mirrors to concentrate the sun's rays to generate power.

This 15th century pharmacy displays a beautiful collection of ancient medicine jars.

Kentucky's anomalous peninsula projecting into the Mississippi River, site of legendary earthquakes and local feuds.

Explore the History & Technology of Electronic Communication

America's first federal monument.

Below a historic English market town lies a secret underground city complete with kitchens, laundries, storerooms, and an underground lake.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

The spot where the namesake of the Douglas fir met his mysterious end on a Hawaiian volcano.

This memorial plaque remembers a strangely shallow maritime disaster known as "Chicago's Titanic."

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

A lonely house representing railroad history tells the stories of those who rode the rails.

America's silhouette includes 100 square miles of wilderness jutting into Canada thanks to an old mapmaking error.

Two provinces and two territories touch borders deep in the middle of the wilderness.

A golden plaque marks the site of the mysterious unsolved assassination of the former Swedish prime minister.

The great polar explorer is remembered in this far northern town, where he embarked on his final expedition.

Unconventional site where the tracks of Zurich tramcars intersect.

The world's longest and deepest train tunnel.

Traversing steep Alpine slopes, this engineering marvel is one of the longest and highest funiculars in the world.

Large Hadron Collider and the Birthplace of World Wide Web.

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

This painted Lego bridge is the product of over a century of locomotive history.

A maze of crosses marks the jumbled divide between the Netherlands and Belgium.

A beautiful maze marks where three countries meet.

A moving memorial to the fallen and missing from WWI trenches.