Popinae were a type of wine bar generally frequented by the lower-classes and slaves, and were simply furnished with stools and tables.
Because they were associated with gambling and prostitution, the popinae were seen by respectable Romans as places of crime and violence.
[1] Juvenal, a 2nd-century CE Roman poet, mentions the popina to be frequented by assassins, some sailors, thieves, fugitive slaves, executioners and coffin-makers.
A service counter in a L or U shape would be in the main room where workers likely served customers food and drink.
[2] Martial, a 1st-century Latin poet, describes a popina that had grown so massive it had occupied the entire street.