The tombstones of Apamea

Legio II Parthica: one of the Roman legions. Its name indicates that it was recruited to fight against the Parthians, but it usually was Rome's strategical reserve, stationed in Italy.

On the courtyard of the museum of Apamea, there is a special collection of tombstones of Roman legionaries, almost all of them belonging to II Parthica. Many of these stones are of about equal size, and it looks as if they belong to a group burial. Is it possible that they belong to soldiers who were killed in action during the civil war between Macrinus and Heliogabalus (218)? Other tombstones appear to date from the reign of Severus Alexander (222-235), while there are some younger and older monuments as well.