The very first documents about the church of St Peter dates back to the late tenth century, however, it is believed that the current appearance is the result of a heavy renovation work took place around 1255. In some municipal codes in fact, illustrates the fact that Innocent IV in 1254 did celebrate the consecration of the church in the same time that they were also consecrated the cathedral of San Rufino and the Basilica of San Francesco. The church is a typical Umbrian-Romanesque building of the thirteenth century, with the characteristic signs of the Benedictine Order. Although this may seem a matter of little importance, it should be pointed out that as belonging to the Benedictine order for this building constitutes a major sign of identity. In fact, following an edict of the thirteenth century, in the city was no longer allowed to build religious orders that were not the Franciscans. The rectangular façade, made with the characteristic pink stone of Mount Subasio, is divided horizontally by a cornice and pilaster vertically, so as to identify three areas of upper and lower, respectively, occupied by three rose windows and entrance doors.