The Negroni cocktail is made of one part gin, one part vermouth rosso (red, semi-sweet), and one part Campari, garnished with orange peel. It is considered an apéritif.
There is a variation of the Negroni with Gran Classico instead of Campari which makes it less bitter. It's often called Negroni Classico.
Old Fashioned glass
Stir into glass over ice, garnish and serve.