This quarter-mile tunnel under the Bluff in Pittsburgh bends at a 45-degree angle.

Home of the only civilian casualty at the Battle of Gettysburg.

This dramatic rail curve was once the target of a failed Nazi attack.

The Master of Magnetism dominates the walls of a scrap metal yard to keep graffiti artists at bay.

The mortal remains of a Russian prince, priest and paranormal investigator who came to America in 1792.

A quiet, gothic haven nestled between Pittsburgh's Squirrel Hill and Point Breeze neighborhoods.

This stretch of beach along California's central coast is a busy highway for the largest seal in the northern hemisphere.

Thousands of turbines whir at at the origin of North American wind power.

Quite simply the largest tree in the world (by volume).

Four hundred granite steps were built into this massive rock by the National Park Service.

A house turned museum is the real-life "home" of the fictional main character of The Wizard of Oz.

A cemetery housing wild west legends in South Dakota.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

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

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

The scene of one of the darkest moments in American labor history has been left essentially untouched since the tragedy.

The highest bridge in America was built for an almost unnervingly small amount of money.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

The hallowed remains of a 900-year old Ancestral Pueblo great house.

The final resting place of the most famous outlaw in the Old West.

The site of Billy the Kid’s most famous escape and the end to the Lincoln County War.