Tunnels

A 500-year-old series of tunnels long believed to be folkloric was uncovered beneath the streets of Puebla.

The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

This frozen tunnel in central Alaska is both an engineering feat and a valuable climate classroom.

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

A centuries-old complex of hand-dug stone chambers has sheltered locals in times of trouble.

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

This hidden stream beneath Indianapolis makes an appearance in the best-selling novel "Underground Airlines."

Underground tunnels once home to crime are now back open to the public.

An ancient tunnel in Jerusalem built to redirect water in the event of a siege is one of history’s great architectural innovations.

This railroad tunnel was once the longest in Massachusetts.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.