Gildas' account implies that a martyrium of Julius and Aaron existed at Caerleon. Bolstering this is the fact that the twelfth-century Book of Llandaff contained a late ninth-century charter that mentions the existence of such a martyrium. This charter described a grant of land to the Bishop of Llandaff Nudd which encompassed the "Territorium Sanctorum Martirum Julii et Aaron" or the "Merthir Iún et Aaron". Possible archaeological evidence for the existence of the early medieval martyrium comes in the form of a ninth-century sculptured cross slab which was found at Bulmore Farm, near the site of the later medieval martyrium, shortly before 1862. Stylistically part of the Gwent Group cross-slabs, most other examples come from major early churches such as St Cadoc's Church, Caerleon, St Arvans Church near Chepstow, and St Tatheus's Church in Caerwent.