What Italian professional football club, founded in 1899, was the first to establish an ultras group?
Fossa dei Leoni:  Established in 1968, it was the first ultras group to form in Italy. A.C. Milan: Associazione Calcio Milan (] ), commonly referred to as A.C. Milan or simply Milan, is a professional football club in Milan, Italy, founded in 1899.
A.C. Milan