Guardialfiera borders the following municipalities: Acquaviva Collecroce, Casacalenda, Castelmauro, Civitacampomarano, Larino, Lupara, Palata.

[4] In 1053 it is likely that Pope Leo IX used Guardialfiera as a base in order to launch an attack against the Normans who had occupied the nearby town of Larino in 1050.

[5] On June 18, 1053, the Norman Count of Apulia, Humphrey of Hauteville, defeated Pope Leo IX at the Battle of Civitate.

The Episcopal Seat of Guardialfiera was established in 1061 by Pope Alexander II likely in recognition of the town's role in the events of 1053.

Many ancient stones carved with pagan and early Christian iconographs dating to the 7th and 8th centuries were incorporated into the present structure.

[3] It is unclear if the present structure was standing at the time of Pope Leo IX’s visit in 1053, but the diocese records clearly show that the designation of Santa Maria dell'Assunta was elevated to a cathedral in 1061 and was presided over a bishop by the name of Peter.

On April 7, 1751, relics of Saint Gaudentius (San Gaudenzio) were transported by two Capuchin friars from the catacombs of St. Priscilla to the Cathedral in Guardialfiera.