In the San Severo area traces of various settlements have been found ranging from the Palaeolithic to the Bronze Age. It was only in the middle ages that the town was developed under the guidance of the Benedictine monastery of Torremaggiore. Situated along the route of the Via Sacra Langobardorum, thanks to the continuous flow of pilgrims on their way to Monte Sant'Angelo, the town soon became extremely important for trade.
In 1230 Frederick II of Sweden handed it over to the Knights Templar, who were followed by the Angevins.
San Severo still has a remarkable historic centre, studded with significant mainly Baroque monuments. The Cathedral, dedicated to Saint Maria Assunta, originates from the XI century, but has undergone numerous transformations, above all in the Baroque period; the church of San Severino, dedicated to the patron saint of the town, has a Romanesque façade from the XII century with a round stain-glass window and a stone archivolt.