Sant'Eustachio is the most famous coffee bar in Rome — a point of pilgrimage for the coffee-serious and a subject of perpetual local debate (Tazza d'Oro partisans insist their espresso is superior). The house specialty is the gran caffè: espresso pre-sweetened and vigorously whipped with sugar before the rest of the coffee is added, producing a frothy, sweet, intense preparation unlike anything in a standard espresso.
The machine is screened from view to protect the technique. The coffee arrives with the foam already formed. You drink it quickly, standing at the counter, and order another. This is one of the genuine coffee experiences of Rome.