Iglesias is a comune and city in the province of South Sardinia, Italy. It was co-capital of the province of Carbonia-Iglesias with Carbonia, and the province's second-largest community. Under Spanish control Iglesias was one of the most important royal cities on Sardinia, and it is the seat of the Roman Catholic Diocese of Iglesias. At an elevation of 190 metres in the hills of southwestern Sardinia, it was the centre of a mining district from which lead, zinc, and silver were extracted.