There is some evidence to suggest that the martyrdom may have occurred not in Caerleon but in Chester. When Gildas first mentions Julius and Aaron, he says that they were martyred in the "City of Legions", or "legionum urbis". That could have referred to a number of legionary fortresses, including Chester and York, both of which carry the name in a number of sources. Archaeological excavations at an amphitheatre in Chester have uncovered a structure that may have been used for public executions in the Diocletian period and the possible remains of an early medieval church, which might be related to a Roman martyrdom site.