The Basilica of San Pelìno is the cathedral of Corfinio and also serves as the co-cathedral for the diocese of Sulmòna-Vàlva. 

The complex includes the church of San Pelino and the Oratory of St. Alexander, both of which were declared national monuments in 1902.

The original basilica was built over the tomb of Pelinus, bishop of Brindisi and martyr in the time of Emperor Julian the Apòstata. In 1075, Bishop Tràsmondo, favoured by the great pontiff Gregory VII, promoted the re-founding of the basilica together with that of St. Pànfilo of Sulmòna. Work began in 1081 and was interrupted in 1092 with the consecration of the single-apsidal transept of the oratory of St. Alexander.

The work was resumed and completed by Bishop Gualtiero, who consecrated the cathedral in 1124. 

Now pause and go through the entrance portal.

The church was renovated internally in the Baroque style between the 17th and 18th centuries. These additions were removed during the 1970s restorations that restored the building to its original Romanesque appearance. 

The interior has three naves divided by pillars supporting pointed arches, with a transept preceded by a triumphal arch. The nave ends with an apse completed in the 13th century. Notable elements for their historic-artistic value include a "Madonna and Blessing Child" in the left transept, a pulpit dating from the time of Bishop Oderisio, two remnants of 13th-century frescoes (a Crucifix with Franciscan saint and busts of saints) and the lìgneo choir of the presbytery made by Ferdinando Mosca in 1738.

The Oratory of St. Alexander, detached from the basilica and concluded by a defence tower, was erected on the right side of the church of San Pelino to house the remains of Pope Alexander I although the exact burial place has never been identified.