Infrastructure

Curious onlookers have suspected this strange structure is a secret government base.

The world's longest tunnel with an undersea section.

The ruins stand as a somber reminder of France’s worst civil catastrophe of the 20th century.

A plaque is all that remains of a lost Oxford transport hub.

This double-arched masonry highway bridge is the only structure of its kind in Minnesota.

It would take you approximately an hour and a half to walk to the end of Mexico's largest pier.

The remnants of this unusual bridge await an uncertain fate.

In a country where driving from one town to another is literally impossible, this small stretch of gravel is a remarkable feat.

It was meant to help transport wounded soldiers to a secret underground hospital.

This tiny 19th-century tunnel was built so a man could move his cows from one field to another.

This Mexico City subway station will make you feel like you've been transported to the London Underground.

The ruins of Vancouver's abandoned heritage railway.

Local legend says Isaac Newton built this footbridge without any screws, bolts, or nails.

A tiny replica of the iconic London landmark hides on the side of the steel structure.

The highest pedestrian bridge in Singapore looks like a series of undulating waves rising between two public parks.

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