Porto Flavia is a former mineral loading port at Masua, in the municipality of Iglesias in south-west Sardinia. Built in 1925 into a cliff above the sea, it was used to load zinc, and its tunnels cut through the rock to an opening high over the water.
Today it can be visited on a guided tour through the mining galleries to the opening that looks out towards the Pan di Zucchero sea stack. Reviewers describe the visit as lasting about an hour, with helmets supplied and entry at scheduled times, so it is worth planning ahead. Tickets are available online, and closed shoes are recommended.
The site is part of the mining heritage of the Sulcis Iglesiente, and the local tourist office in Iglesias promotes it among the town’s mining sites. Parking close to the entrance is limited, so allow extra time for a walk from the larger car park.