A Catholic Ceremonies is performed in a Catholic Church. It is a sacrament performed during the Holy Mass by a Priest. This kind of ceremony requires special paperwork to be done in addition to the Civil documents. Catholic Ceremonies can be just religious or concordatory which means that the catholic ceremony will be performed together with the legal one.
If one of you are not Catholic you are allowed to get married but you should provide this additional document which testify that your wedding can be performed by the Italian religious authorities.
This certificate is usually issued by the local bishop of your country, but your local Priest will easily help you to obtain the document. The Permission of mixed religion has to be sealed or stamped by the Bishops Parish office.
Please note that in accordion with your local Parish you have to attend the pre maritial class.
If one of the Parties has been divorced, the Italian Catholic Church don’t allow you to re-marry in a Church, unless the Rota (the only Institution legally able to officially cancel previous catholic marriages) had previously cancelled your wedding.
In case the couple has been previously civilly divorced and want to get married again in the Church it is required a civil reconciliation certificate.
The religious Documents should not be done more than 3 months, and the legal documents not more than 6months in advance or they expire.
When you have collected all the paperwork from your priest you should send all the originals directly to the Italian Curia.
The catholic ceremony cannot be held in other place if not in a Catholic Church, but there is nothing to be worried ad there are so many beautiful Churches in Italy, different style and sizes.