Vigiles or more properly the Vigiles Urbani or Cohortes Vigilum were the firefighters and police of ancient Rome.
Graffiti from wardroom of 7th Cohort
A cohort was a standard tactical military unit of a Roman legion. Although the standard size changed with time and situation, it was generally composed of 480 soldiers. A cohort is considered to be the equivalent of a modern military battalion. The cohort replaced the maniple. From the late second century BC and until the middle of the third century AD, ten cohorts made up a legion. Cohorts were named "first cohort", "second cohort", etc. The first cohort consisted of experienced legionaries, while the legionaries in the tenth cohort were less experienced.
Denarius, struck under Mark Antony in honor of the cohors speculatorum