As the world’s largest developing country and infrastructure powerhouse, China not only has an extremely high demand for concrete but also increasingly focuses on enhancing the durability of concrete to delay aging and improving its resistance to seawater corrosion. Ancient Roman concrete, reflecting the wisdom of the Romans, possesses remarkable durability and corrosion resistance, which has attracted extensive research from scholars across various fields. By collecting petrological information from the volcanic area of the Roman volcanic province and comparing the mineralogical changes of ancient Roman concrete before and after exposure to seawater, it is found that the use of high-alumina volcanic ash and the formation of secondary aluminum silicate minerals are crucial for the high durability and corrosion resistance of ancient Roman concrete. The study discovers that ancient Roman concrete contains materials such as quicklime, volcanic ash, and ceramic fragments. The reaction between high-alumina volcanic ash and quicklime, as well as ceramic fragments in the aggregates, form a structure composed of C-A-H, C-S-H, and C-A-S-H, which effectively bond the aggregates. Over time, these C-A-S-H compounds can crystallize into minerals such as tobermorite and phillipsite. These special minerals not only exhibit high mechanical strength but also adsorb harmful ions during interaction with seawater, thereby protecting the concrete from seawater corrosion. Additionally, the material composition of ancient Roman concrete has a unique self-healing mechanism, allowing it to spontaneously fill cracks. As an artificial rock, ancient Roman concrete demonstrates unique advantages in durability and corrosion resistance. A systematic study of its petrological characteristics can provide theoretical guidance for the development of modern concrete and other geological materials.