A tiny bit of background from Mental Floss … the histories of cocktailing can be fascinating.
Count Camillo Negroni gets credits for creating this aperitif around 1919. As the story goes, Negroni really loved to throw back an Americano (Campari, sweet vermouth, and club soda), but he wanted a little extra zing in his glass. He asked a bartender to replace the club soda with gin to give the mixture some added kick, and the Negroni was born.
It just needed more firewater to be a popular cocktail.
1 ounce London dry gin
1 ounce sweet vermouth
1 ounce Campari
Orange peel, sliced.
Stir over ice and strain into a glass, preferably one filled with ice. Garnish with a fat swath of orange peel, [which can be flamed if you want to impress anyone with your mixology game].