Storage Vault

Benefit
An Adv. Iron Mine allows you to harvest Iron at twice the rate of a normal Iron Mine.

Description
The Underground Warehouse allows you to store 2000 of each resource. And through the miracle of modern technology, all that loading and unloading of crates and barrels can be done with only 4 workers! Better still, most of the building is underground, leaving you more room on the surface. The Underground Warehouse, you probably haven't heard of it.