The first steel dam in the world and the only one still functional in the United States.

This Boeing KC-97 tanker is now a restaurant for aviation lovers.

This spot memorializes one of the greatest plays in NFL history, unless you happen to be a Raiders fan.

This icon of the Atomic Age now lays dormant.

Sections of the iconic limestone columns have been left uncleaned as a reminder of the city's polluted past.

Pittsburgh's literal underground railroad.

This picturesque stream was up until recently the site of a ten story mountain of slag and sewage.

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

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

There aren't too many operational funiculars around, but Pittsburgh has two!

The only way to see Pittsburgh is from the top of this lookout point, just like the ancient members of the native peoples did.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

An architect transformed this abandoned cement factory into his castle-like workshop.

A picturesque example of brute-force engineering conquering nature.

A modern Nordic Pompeii on the Icelandic island of Heimaey.

The largest permanent Monopoly board makes one of the longest games even bigger.

It took years to decode its mysterious messages.

The site of Japan's first major environmental disaster.

The only geyser in the state of Pennsylvania is caused by pressure from an abandoned coal mine outside of the ghost town Centralia.

Abandoned silver mine strewn with wrecked and twisted structures.

This giant steer-skull edifice refuses to die.

A ghost town that held steady longer than most, but finally gave up the ghost.

The hellish conditions of this abandoned mine that snakes beneath the Pacific Ocean gave it its diabolic name.