Tecniche e materiali da costruzione nella Milano antica e medievale

[Autom. eng. transl.] The city of Milan preserves an extraordinary historical and architectural heritage, consisting of a large number of ancient religious buildings, in most cases built at the origins of Christianity and transformed into new forms in the Romanesque period. In the paper the results of the research work, conducted by the writer, on the construction techniques of the main buildings of worship in the city (S. Ambrogio, S. Simpliciano, S. Giovanni alle Fonti, S. Nazaro Maggiore, ... ), trying to highlight the main transformations between Late Antiquity and Romanesque. A large number of stone materials were used in Roman architecture in Milan and Lombardy, materials made available thanks to the geological variety of the territory. The Alps supplied granites, diorites, gneisses, marbles; the limestone, dolomite, sandstone (Mesozoic) and conglomerate (Quaternary) pre-Alps; the Padana plain pebbles, gravels, sands and clays of alluvial deposits (Quaternary). Each stone was mostly used in areas adjacent to the quarries, reaching the cities (Comum, Ticinum, Mediolanum, Bergomum, Brixia) through the waterways; in the cities of the plain (Placentia, Cremona, Mantua) bricks made from local clay were favored. In Milan, as a capital city, stones from greater distances were also used (limestone from Veneto and Friuli). Despite the difficult supply, the white marbles of the Apuan Alps and the colored marbles of the eastern Mediterranean were widespread in Mediolanum and in many other Lombard sites. The materials quarried by the Romans were continuously used also in the following centuries.