 The most widely accepted theory, based on documents dating back to the early 16th century, is that the town is named after Alfonso Calcagnini, credited with reclaiming land from the marshes on which the town was founded.The second hypothesis is attributed to Antonio Polloni, who in his 1966 book "Toponomastica Romagnola" (“The geographical structure of the region of Romagna”), postulates that the name derives from the Latin term "fossa" (man-made ditch, channel), and that only later, by coincidence, it was influenced by the name of Alfonso Calcagnini.Alfonsine was founded in 1464 when some land north of the city of Fusignano, consisting primarily of wetlands, was donated by Borso d'Este to Teofilo Calcagnini who began an aggressive reclamation process.