The purpose of this work is to carry out an accurate and extensive environmental analysis of the steel production occurring in in the largest integrated EU steel mill, located in the city of Taranto in southern Italy. The end goal is that of highlighting the steelworks’ main hot spots and identifying potential options for environmental improvement. The development for such an analysis is based on a Life Cycle Assessment (LCA) of steel production with a cradle to casting plant gate approach that covers the stages from raw material extraction to solid steel slab production. The inventory results have highlighted the large solid waste production, especially in terms of slag, which could be reused in other industries as secondary raw materials. Other reuses, in accordance with the circular economy paradigm, could encompass the energy waste involved in the steelmaking process. The most burdening lifecycle phases are the ones linked to blast furnace and coke oven operations. Specifically, the impact categories are influenced by the energy consumption and also by the toxicity of the emissions associated with the lifecycle of steel production. A detailed analysis of the toxicity impacts indicates that LCA is still not perfectly suitable for toxicity assessments and should be coupled with other more site specific studies in order to understand such aspects fully. Overall, the results represent a first step to understanding the current levels of sustainability of the steelworks, which should be used as a starting point for the development both of pollution control measures and of symbiotic waste reutilization scenarios needed to maintain the competitiveness of the industrial plant.