Roman Catholic Diocese of Aosta

The Italian Catholic Diocese of Aosta has existed in its modern form since 1817. It is a suffragan of the Archdiocese of Turin.
The diocese of Aosta was founded no earlier than the 5th century. At that time it was a suffragan of the diocese of Milan. On 13 June 867, Pope Nicholas I made it was a suffragan of the Archbishop of Vienne, and it is known that in the 11th century it was a suffragan of the diocese of Tarentaise, a province created between 794 and 811. It then became subject to Milan again, but was restored to Tarentaise. The diocese of Aosta was suppressed by order of the Emperor Napoleon I, in 1802, an order which was given canonical effect by Pius VII in 1803.

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