The first tunnels date back to 60 B.C. They were consistently dug as limestone quarries and by the 18th century, the caving-in of some of these quarries posed safety threats, so the government ordered reinforcing of the existing
Los primeros túneles datan del 60 a.C. Fueron consistentemente excavados como canteras de piedra caliza y para el siglo XVIII, los derrumbes en algunas de las canteras implicaban riesgos de seguridad entonces el gobierno