The study presented here is part of a civil engineering research project having the goal of developing a structural diagnosis method for masonry lighthouses built in France at the end of the 19th century. Its purpose is to describe the design and calculation methods used by engineers of the time to size the structures, and to compare them with current European standards. The article presents a case study, the Ile Vierge lighthouse, 82m high, built between 1897 and 1902, with cracks in the upper part. Its engineers used the new materials of the second half of the 19th century (cement, wrought iron, reinforced concrete) and a local stone called kersanton. The stability of this tall lighthouse under wind loads led to discussion among engineers of the “Service des Phares et Balises” who worried about the risk of excessive oscillations of the tower. The standard wind action defined in Eurocode 1 is applied to the structure and detailed calculation results are given. A comparative analysis of the ancient and modern methods is presented. The wind action cannot explain the structural damage observed on the lighthouse.