There are 2,000 of these ancient tunnels throughout Central Europe, especially in Bavaria. No one is sure who made them or ...

Huge ancient underground tunnels have been discovered in Brazil and Argentina, and the source of these huge structures is not believed to be due to humans or natural geological processes. Reaching ...

Norway is building what is to become the longest and deepest road tunnel under the sea. The Rogfast project, measuring 26.7 kilometers (about 16.5 miles) and descending to 392 meters (nearly 1,300 ...