Engineering

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

Once the largest gravity dam in the world.

This unusual three-way wooden foot bridge spans two rivers at once.

At the largest railway museum in the United States, you can see everything from an early steam engine to a functioning Thomas the Tank Engine.

A railroad lift bridge that was only lifted once and became obsolete before construction was finished.

This remnant of an old railroad is the tallest surviving wooden trestle bridge in Victoria.

An enormous Soviet aircraft, the only one of its kind, stands at the deserted shore of the Caspian Sea.

A supersonic jet stands on a pedestal in this rural village as a monument to military aviation.

Part of a highway network meant to connect Miami to Montreal, this 10-mile stretch of road made from red bricks is still around 100 years later.

A waterway covered over after the Industrial Revolution has been unearthed and cleaned up, for the enjoyment of fish and humans alike.

If it hadn't been caught in time, a flaw in the design of this Manhattan skyscraper could have led to its collapse.

A fantastic example of Victorian railway engineering with two unusual decorative features.

Built to transport German U-boats through the never-completed Masurian Canal, the locks near this Polish village are now home to a rope course.

Nearly 800 years old, this river lock is now a public park with a former fortified island.

A network of underground water channels that dates back to the Middle Ages.

Once considered a marvel of engineering, this 107-mile canal played an integral role in building New York City.

This hand-carved wooden carousel in the Story City North Park was built in 1913.