Engineering

This tower was once used to create ammunition for early settlers.

This unique structure is the only one of its kind in Virginia.

This structure, built more than 60 years ago to manage devastating seasonal floods, is known to attract a rare species of freshwater dolphin.

Dozens of rockets and missiles are on display outside a testing facility in the Utah desert.

This concrete monster of a wreck lies in the mouth of Langstone Harbour as a monument to the incredible history of D-Day.

This 900-foot structure with 20 arches crossing a Scottish river was built in the late 19th century.

This windmill was used for well over a century.

This unique style of bridge is the last of its kind and runs over the straightest canal in Britain.

The departure point for the first return flight across the Atlantic.

Located more than 600 feet beneath sea level, this tunnel boasts the world's first undersea roundabout.

The bridge that cost Germany a World Heritage Site.

This incongruous small ferry across the Willamette River north of Salem, Oregon has been operating continuously since the 1850s.

An isolated "phantom bridge" doomed to crumble into ruin.

An out-of-the-way state park in Oregon that features both a picturesque waterfall and the ruins of a hydropower plant.

A giant glider—designed by the father of the Rubik's Cube's designer—now soars within a shopping mall.

The remains of a 19th-century carving of what was to be a signal light on the Firth of Forth Estuary.