This 19th century hydroelectric powerhouse was the first of its kind.

The tallest bridge in California was constructed for a project that was eventually cancelled.

This former boomtown "island" is now submerged below Folsom Lake.

I Street Bridge is the heaviest swinging center bridge in the United States.

The California capital city once stood 10 feet lower than it does today.

This 19th century train workshop is a treasure trove of railroad history.

A dentist's hated concrete colossi are now beloved icons of the community.

A beautiful ruin of a 14th-century Plantagenet castle built by a medieval mercenary.

This medieval tower is all that remains of the castle where Joan of Arc was held before being burned at the stake.

This giant temperature attraction created some giant electric bills.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

A German apartment building hosting as many trees as human occupants.

A former Nazi lookout tower with a magnificent view of the Rhineland.

The oldest inn in England served brew to the crusaders.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

1898 German railroad depot museum with working engines, steam train excursions, and hands-on displays.