Trek 6, Masua & Porto Flavia: Porto Flavia is a sea harbour located near Nebida. Built in 1923–24, it served as the mineral production hub of Masua in the west coast of the Sardinian Sulcis area. It is named after Flavia Vecelli, the daughter of Cesare Vecelli, who engineered and designed the harbour. The harbour’s characteristics make it unique in the world, and at the time of its construction it was an outstanding engineering feat. Porto Flavia’s importance decreased in the 1960s after the decline of mining activity in Sulcis, and it was closed in the 1990s when mineral production in Masua ceased. Today, it is owned by IGEA SpA, a public company charged with the restoration and preservation of the old mining plants. Porto Flavia is a UNESCO-protected site, and is one of the suggested destinations for tours of minerary and industrial archaeology sites in the region. Daily tours are held in the tunnel, guided by former workers or mining technicians of IGEA. The Masua hub was a complex of several mining operations in the Sulcis area, a region of Sardinia rich in coal, sulphur, barium, zinc, lead, silver and other metals. Extraction began in 1600, but became economically relevant only in the early 1900s when the mining business in the whole region experienced a quick expansion. The extraction, especially of the coal caves, was operated on a low-technology basis until the early 20th century. Since the late 1800s metal-gathering enjoyed more modern techniques, as it was controlled mostly by rich north-European corporations more willing to commit money in improving the mining efficiencyPorto Flavia.In 1922, the Masua mines were acquired by the Belgian Vieille Montagne Company, and exploitation increased with the growing need for zinc and lead for reconstruction after World War I as well as because of technological advance in steel alloys. The zinc and lead ore was extracted in the mines by male miners (aged 16 and above), processed by female workers and children in a centralized “washing plant” (called Lavatoio), and was finally stored.