The earliest known Bishop of Ischia, Pietro, was present at the Third Lateran Council of Pope Alexander III in 1079.

[7] The cathedral, dedicated to the taking up (Assumption) of the Virgin Mary into heaven, is located in the Castello Aragonese, at the eastern tip of the island of Ischia.

In 1848, the cathedral was served and administered by a Chapter, composed of three dignities (the Primicerius, the Archdeacon, and the Archpriest) and sixteen Canons.

In order to finance the operation of the seminary, two parishes were suppressed, Santa Barbara in the Castello Aragonese, and San Domenico in Campagnano.

[10] On 23 July 1762, a major earthquake struck Ischia, without loss of life, but with the destruction of the parish church at Casamicciola.