The pit "Santa Barbara" is part of the mine of San Giorgio (zinc), cultivated since ancient times. Built in 1870 in form of a medieval castel (as tribute to the nearby ancient town of Iglesias), it contained a large steam machine that moved the mine cage down and up the shaft. The mine stopped all activities in the forties of XX century. The pit was sealed with concrete, the heavy machinery was scrapped. The spectacular "castle" is now in ruins but still charming and it's visible from many kilometers. It is also called "Sa Macchina Beccia" ("the old machine", in sardinian language).