Marvels of Underground Italy. Small towns, Rome, and the Gulf of Naples offer intriguing underground tours. The region of Abruzzo is home to the Tunnels of Claudius, a subterranean water system consisting of several parallel passages and vertical shafts passing through solid rock located throughout the towns of Avezzano and Capistrello in the Province of L’Aquila.
The main tunnels are approximately 3.7 miles in length and were built by Roman Emperor Claudius in 52 A.D. to partly drain water in the Fucine lake in order to mitigate flooding of villages nearby. The massive engineering feat was constructed without any machines by over 30,000 workers and slaves. It was built in just 11 years and was the longest tunnel ever built until the construction of the Fréjus Rail Tunnel in 1871, according to Wikipedia.
