Basilica of San Tommaso Apostolo, Ortona

The Basilica of San Tommaso Apostolo ("St. Thomas the Apostle"), also Ortona Cathedral (Basilica-Concattedrale di San Tommaso Apostolo; Duomo d'Ortona), is a Roman Catholic cathedral and minor basilica in Ortona, Abruzzo, Italy, famous for holding the relics of Saint Thomas the Apostle. It was formerly also the episcopal seat of the diocese of Ortona and is now a co-cathedral in the diocese of Lanciano-Ortona.

The Basilica was built on the site of an ancient Roman temple. Destroyed by the Normans in 1060, it was rebuilt and dedicated to Santa Maria degli Angeli in 1127. Since 1258 the Basilica has housed relics of Saint Thomas. The cathedral has suffered damage from military attacks by the Ottomans in 1566, the French in 1799 and from fighting during the Battle of Ortona in 1943.