The Americano is an IBA official cocktail[1] composed of Campari, sweet vermouth, and for the sparkling version, club soda and garnished with a slice of lemon or an orange twist.

In the 1860s, an American man, who was under the impression that Campari was a long drink, ordered it, hated it, and said it would be better served iced and fizzy.

He ordered a Campari and soda which became too bitter; after a few iterations he and the esteemed bartender decided on Vermouth as the perfect blend.

[4] It is the direct descendant of the "Milano-Torino" which consisted of Campari, the bitter liqueur from Milan (Milano) and Punt e Mes, the vermouth from Turin (Torino) but lacked soda water.

In The Tourist, Elise and Fred each had an Americano (or two) before their fancy dinner at a Venetian restaurant, and resumed drinking that post-dinner back in their hotel room.