Few cocktails have achieved quite as much with as little as the Negroni. Gin, Campari and sweet vermouth, traditionally poured in equal measures, stirred over ice and finished with orange: it is one of those rare drinks where simplicity has become its greatest strength.

And, more than a century after its creation, the Negroni has never felt more relevant. Bartenders around the world have used that beautifully straightforward 1:1:1 formula as a canvas for experimentation, switching spirits, introducing local ingredients and occasionally removing the alcohol altogether.

For Negroni Week, which runs from 21–27 September, London Italian institution Sale e Pepe is taking that idea a little further. Bar Director Pietro Collina has created five interpretations inspired by different corners of Italy, available at both the original Knightsbridge restaurant and its seafood-focused sister restaurant, Sale e Pepe Mare at The Langham.

From Florence to Messina, Portofino to Trieste, here are the five to try.

There is only one sensible place to begin: Florence. The Negroni is generally traced back to the Tuscan capital in the early 20th century, when Count Camillo Negroni is said to have asked for his Americano to be strengthened with gin in place of soda water.

Sale e Pepe's Florence Negroni keeps things reassuringly traditional. Bombay Sapphire Premier Cru is combined with Campari and Cinzano 1757 Rosso Vermouth, retaining the classic equal-parts structure that made the drink famous.

It is bitter, botanical and unmistakably Italian, and proof that sometimes a classic doesn't need reinventing.

Head south to Sicily and things become rather more adventurous. Inspired by the White Negroni, the Messina swaps the familiar ruby-red combination for something brighter and more aromatic.

Palmaráe Premier Cru Gin forms the base, joined by saffron-infused Cocchi Americano and the distinctive bitterness of Suze. The saffron is the clever touch here, introducing a flavour closely associated with Sicilian cooking while giving the drink an added layer of spice and complexity.

The result is recognisably a Negroni in structure and spirit, but quite different in the glass.

If the Messina looks south, the Portofino transports the Negroni to the Ligurian coast.

Bombay Sapphire, Campari and Cinzano 1757 Rosso Vermouth provide the familiar foundations, before fig leaf liqueur introduces a distinctly Mediterranean character. Fig leaves have a wonderfully unusual aroma — green, slightly coconut-like and evocative of hot Mediterranean gardens, making this perhaps the most summery drink of the five.

Order one, close your eyes, and Knightsbridge might just begin to feel a little more like the Italian Riviera.

Italy takes its coffee seriously, but few cities can claim a relationship with it quite like Trieste. Its historic port helped establish the city as one of Europe's great coffee centres, and that heritage provides the inspiration for Sale e Pepe's darkest Negroni.

Bombay Sapphire, Campari and Cinzano 1757 Rosso Vermouth are joined by tobacco liqueur and cold-drip coffee, adding roasted, smoky and aromatic notes to the cocktail's familiar bitterness.

This is the one to order later in the evening: richer and more brooding than the classic, with the coffee and tobacco pushing the Negroni firmly into after-dinner territory.

Finally, proof that taking the alcohol out of a cocktail needn't mean taking away the ceremony.

Sale e Pepe's No-Groni offers an alcohol-free interpretation of the Italian classic, designed to retain the bitterness and complexity that make a Negroni such an effective aperitivo in the first place.

And perhaps that is the best demonstration of why the Negroni has endured. More than 100 years after its creation, its basic formula can be taken from Florence to Sicily, Liguria and Trieste — or stripped of alcohol entirely, without losing the character of the original.

All five Negronis are available for £15 throughout Negroni Week, from 21–27 September, at Sale e Pepe in Knightsbridge and Sale e Pepe Mare at The Langham, London.