The royal diploma of Berengario I of August 14, 908 is up to today the first source to attest the Benedictine coenobium of San Sebastiano, built by the Earl Gariardo, in the “castrum” of Fontaneto. The stones of the castle area are precious witnesses of the past. Roman materials and fragments of liturgical vestments and church plates of the IX century, unusual in the Novara territory, on one hand induce to formulate hypothesis of research on their origins, on the other hand confirm the cultural centrality of the ancient Benedictine and earl’s seat in the Middle-Ages, in contact with the most cultured environments. Different studies reveal that we learn that Fontaneto is already mentioned in a diploma of the year 945, when “Gariardo è detto comite de Castro Fontaneto” (“Gariardo is named earl of the Fontaneto castle”), and afterwards also in two agrarian pacts of the years 1172 and 1222.rispectively as “community of Fontaneto” and “burgh of Fontaneto” (Prof. Ivana Teruggi). In the Middle-ages, this locality assuredly was of prime importance, so much that the Archbishop of Milan summoned the important “Sinodo di Fontaneto” (Synod of Fontaneto) at the Abbey in the year 1057. In that occasion the bishops decided to fight the movement of the Pataria, led by Arialdo and Landolfo. Many political-religious facts followed each other in this burg over the centuries. In 1456 Filippo Maria Visconti builds up an important Sforza-style castle on the remains of the previous buildings, whose wide traces can still be seen today. The “lobbia” (“loft”), supported by serizzo-stone trusses, and the terracotta frieze with a long series of coats of arms, painted in fresco in the first decade of the sixteenth century are outstanding. On the 13th of June 1639, Fontaneto suffered a French-Spanish siege: a long day of battles led to the destruction of the houses, the parish church belfry collapsed and the corner towers of the castle suffered serious structural damages. Within a few years, around the late 1600’s, the castle was no longer there; only the palaces and noble houses survived. The Visconti family stayed in Fontaneto throughout the 18th century; later the castle was subdivided into parts which still remain under private property.