The Comacine masters (magistri comacini) were early medieval Lombard stonemasons working in a region of excellent building stone who gave to Lombardy its preeminence in the stone architecture that preceded Romanesque style.
Their masons' marks have suggested arcane meanings for some enthusiasts. The name comacini Romantic historians of the nineteenth century traced to the location where they supposedly had their headquarters,the minute Isola Comacina in Lake Como, alleged to have been a safe haven during the Lombard invasion; a more inventive etymology derives from a supposed Latin expression cum machinis, referring to their tools.
The first mention of Comacine masters was in an edict of 643 of the Lombard king Rothari, which concerned itself in Lombard fashion mainly with the indemnity that would be due should a house collapse which had been built by a magister comacinus for a patron ad opera dictandi ("commissioning the works"). The reference has been interpreted as granting certain privileges to magistri comacini, but the context shows that modern readers are correct in interpreting the key word comacini simply as "masons". Comacini are also mentioned in a passage in the Memoratorium of Liutprand the Lombard.
The survival of brotherhoods of the comacini are based on the hypothesis that the Roman secrets of masonry construction were never utterly lost in Italy but were passed on by the mason brotherhoods, which were supposed to be among the numerous documented collegii in which workingmen joined together for mutual protection, fraternal banqueting and eventual support of their widows throughout the Roman Empire, sometimes associated together as masters of the arcana or "mysteries" of their craft. Each such confraternity was composed of men (never women) located in a single town, and was made up of men of a single craft or those worshipping a single deity, free, freedmen and slaves together, forming a bond very like the image of a city, always under the uneasy surveillance of officialdom. Such, it supposed, were the comacini whose geographical center in the Early Middle Ages originated in Lombardy, in Como and Pavia.