The watery grave of an impractical idea.

There's a crumbling old mansion inside the Smithsonian National Zoo.

The only surviving leech house in the United Kingdom was a home for bloodsucking worms until the 1900s.

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

An opal mining town in the middle of Australia where people live, worship, and shop underground.

These chunky stone towers out in Lake Michigan are the key to Chicago’s drinking water.

A mass grave for victims of an airline disaster that led to much-needed safety improvements for commercial flights.

This recipe is set in stone.

The forgotten remnants of a land-to-sea cable car that was once unique in the world.

One of the few surviving examples of the first lock and dam system built on the Ohio River.

A mysterious shape catches the eye in this 16th-century painting.

The island houses the ruins of a secret nuclear fusion lab that once employed high-profile Nazi scientists

Florence’s mother built a stairway down to her daughter’s coffin so she could comfort her during storms.

The remains of an abandoned dinosaur theme park litter the woods just off the highway.

This cliff-face port is considered a masterpiece of mining engineering.

The world’s highest ski resort was deserted after an 18,000-year-old glacier melted away.

Winter weather reveals a large Italian marble crucifix drowned beneath Lake Michigan.

This quaint funicular has been ferrying people up and down an English valley since the Victorian era.

The fictional star of "Breaking Bad" is memorialized with a real-life gravestone in his hometown.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.

It took over 100 years to decode this enigmatic epitaph for two buried brides.

This abandoned secret city is a crumbling wonderland of Soviet ruins.

The oldest living cultivated fruit tree in North America.