A tunnel approximately 600 metres long, dug out of the rock by the miners, appears halfway up a cliff, offering a breathtaking view of the captivating Pan di Zucchero sea stack, a 132-metre natural monument shaped over time. The mine of Porto Flavia, on the promontory that dominates Masua, in the territory of Iglesias, built between 1922 and 1924, was a daring enterprise suspended between sky and sea, that made it possible to load minerals directly onto the ships, destined for the northern European foundries, drastically reducing time and cost of transportation.

Two tunnels, one on top of the other, overlook the sea and are interspersed with silos that can contain up to 10 thousand tonnes of material. The silos were loaded in the upper tunnel, while from the lower one, equipped with a conveyor belt, lead and zinc were loaded onto steamboats, thanks to a movable arm.