Born in Naples, his father Diego's brother was Giuseppe Valletta.
Well-versed in languages and study of ancient monuments, Francesco joined his father in selling off Giuseppe's estates and collections to cure the family's dire financial issues.
He became a great friend of Matteo Egizio and kept up a long correspondence with Ludovico Antonio Muratori.
[3][4] He wrote many poems in Latin, ancient Greek and Italian which were published in several collections during his lifetime.
He was initially also going to be its permanent secretary, but his age and failing health meant he could not keep up that role, ceding it to Pasquale Carcani.