Megastructures seem to be a trend in Asia with China building a $6.74bn underwater bridge with tunnels and man-made islands and now Japan is getting in on it with their own long-distance tunnel ...

The Delaware Aqueduct is a prime example, serving as a vital lifeline for one of the largest cities in the world. While the Seikan Tunnel in Japan, once the world's largest underwater railway tunnel ...

One of the last major Japanese megaprojects of the 20th century, it includes a three-mile bridge and a six-mile tunnel beneath the bay - earning it the title of the fourth-longest underwater ...

The relics are grim remnants of the vast tunnel network dug by the Imperial Japanese Army under Shuri-jo castle before the fierce Battle of Okinawa in 1945. Previously closed-off parts of the ...

It is never easy to accurately locate underwater heritage sites even in Japan, which is surrounded by the sea. A survey conducted by the Agency for Cultural Affairs through local governments found ...