They say it was invented in Florence's Caffé Giacosa about 1919, when Count Negroni decided his favourite americano could use a little more kick, and asked the bartender to put some gin in it. Now the accepted recipe is equal parts gin, red vermouth and Campari. Sometimes you get a slice of orange.
An 'erroneous Negroni' (Negroni sbagliato) uses sparkling wine instead of gin (an error indeed, we suspect). If you use vodka, it's a negroski.
Images by: Geoff Peters