For some of the largest Italian weddings we have coordinated the past fifteen years we have used wedding catering with famous chefs that move with their entire mobile kitchen to the area where the reception will be taking place. This is not because there are not any good wedding restaurants in that part of Italy but because of the exceptional reputation of these wedding caterers.
Generally speaking, however, most Italian restaurants do not offer wedding catering services. They expect the wedding reception to take place on their own premises. Most Italian reception locations have much sunlight, open up directly to the outdoors into a garden or private park and are easy to serve from the commercial kitchen that is attached.
Wedding caterers in Italy are for the most part well known wedding restaurants that serve other reception locations that are relatively near their own premises. There may be a castle or villa that does not have a commercial kitchen that is large enough to prepare all of the wedding food for the wedding guests that are expected.
Ancient European Castles almost always are not very well suited for large catering services unless the owners have gone through the expense to redesign their interior dramatically and with walls that are over one meter in diameter that can be very expensive anywhere in Europe.