An extensive Roman military complex once occupied the level plain to the south of Llanfor. It was first recognised and recorded by Cambridge University in 1975-6, during aerial reconnaissance, when extensive parchmarks were recognised in the fields. These were mapped from aerial photographs by the Royal Commission in 1997, in order to guide geophysics and trial excavation by Snowdonia National Park and the Gwynedd Archaeological Trust in 1997 prior to the establishment of the National Eisteddfod on site (Crew & Crew 1997; Hopewell 2005, 247-53). The Roman military complex was only seen again from above as an exceptional set of cropmarks during the dry summer of 2006, during Royal Commission aerial reconnaissance (image refs: AP_2006_4015-4034).

Four separate military enclosures are known. At the centre of the complex is a large temporary camp (NPRN 308244). This overlaps a second, smaller, camp to the north-west (NPRN 308245) and is abutted by a large fort on the south (NPRN 401826) and a polygonal enclosure on the west (NPRN 401825). The fort and enclosure occupy the fringes of the plain where steep scarps rise above the various river floodplains. The site chronology is uncertain, although it is thought that the large fort represents a troop surge immediately following the Roman conquest. It is possible that the large camp is later than both the fort and polygonal enclosure (Hopewell 2005, 251-2) and it could be associated with unrecorded campaigns following the initial conquest. A longevity of Roman occupation on site is suggested by the presence of a vicus or civilian settlement set out along a road to the north-west of the fort, with individual building plots and hearths revealed in the geophysics.

Sources: St Joseph in the Journal of Roman Studies 67 (1977), 149-50 fig 15
Crew & Crew in Archaeology in Wales 37 (1997), 13-20
Hopewell in Britannia 36 (2005), 225-69
also reports in: Britannia 29 (1998), 368 fig 3
34 (2003), 296 fig 3

John Wiles 14.05.07; T. Drver RCAHMW, 29th April 2009.