Built on a limestone foundation, Valletta housed defense systems in deep tunnels during WWII that saved Malta and Allied ...

Police in Chihuahua, Mexico, say they are investigating social media claims of a possible second illegal tunnel between El ...

Under Inca rule, Cusco was developed into a complex urban centre with distinct religious and administrative functions. It is renowned for its architectural and cultural heritage and was surrounded by ...

Urban planners from Mexico City to Toulouse are adopting the high-flying mode of transit. Will it catch on elsewhere?

An underground tunnel network long rumored thanks to drawings by Leonardo da Vinci under Milan’s Sforza Castle are proven to ...

OKC Mayor Patience Latting described the city's underground Metro Concourse network as "the largest pedestrian tunnel system ...

clodio/iStock Editorial / Getty Images Plus ... buried a foot or more under the ground. Some of these, the researchers say, can be linked to secret military tunnels that can also be seen ...

Under Inca rule ... The latest discovery of the tunnels highlights the advanced nature of Inca civilisation as the tunnels likely served as a communication system across the city.

An underground tunnel network long rumored thanks to drawings by Leonardo da Vinci under Milan’s Sforza Castle ... twin of the castle’s underground system for museum visitors.

The agency overseeing construction of the new rail tunnel connecting New Jersey and Manhattan on Monday awarded a $1.8 billion contract for the connection on the tunnel’s New York side.