The province has a total population of 387,649 inhabitants as of 2017[update] and spans an area of 2,599.58 square kilometres (1,003.70 sq mi).

The province contains the National Archaeology Museum of Abruzzo, in Italian the Museo Archeologico Nazionale d'Abruzzo, which contains items from the area prior to Roman rule.

It was conquered by the Romans in 305 BCE but after the fall of Rome in 476 CE, Theodoric the Great gained ownership of the city and it was subsequently used as a Lombard fortress.

The provincial capital is Chieti, situated on a ridge a few miles inland and just south of the River Aterno-Pescara, which flows into the sea at nearby Pescara.

Pietro e Paolo and the adjoining houses are extensive substructures (in opus reticulatum and brickwork) of the 1st century CE, belonging to a building erected by M. Vectius Marcellus[6] and Helvidia Priscilla.

In the first half of the 15th century its walls were built, and during this period Ortona fought with the nearby town of Lanciano in a fierce war that ended in 1427.

On 9 September 1943, the royal family of the House of Savoy left German-occupied Italy from the port of Ortona.

The defensive Gustav Line was established by the Germans at Ortona, extending towards Cassino on the opposite side of Italy.

The Coronation of the Virgin sculpture group in the portal lunette is also magnificent, attributed to the school of Nicola di Guardiagrele.

Under the colonnaded portico, next to the lateral door, is the splendid fresco by Andrea De Litio (1473) portraying Saint Christopher.