"The plain, too, was bored and delved. Shafts were driven deep into the ground; their upper ends were covered by low mounds and domes of stone, so that in the moonlight the Ring of Isengard looked like a graveyard of unquiet dead. For the ground trembled."
—The Two Towers
The Mineshaft is a resource building of Isengard which can be built at a main base/outpost and settlements. Unlike Dwarven Mineshafts, the Isengard Mineshafts are not able to be garrisoned with units to transport them across the map.