Segontium
SEGO´NTIUM a city in the NW. part of Britannia Secunda, whence there was a road to Deva. (Itin. Ant. p. 482.) It is the modern Caernarvon, the little river by which is still called Sejont. (Camden, p. 798.) It is called Seguntio by the Geogr. Rav. (5.31).
[T.H.D]An auxiliary fort of 2.2 ha in the command of Legio XX V.V., garrisoned by a cohors milliaria equitata and in the 3d c. by the quingenary Cohors I Sunicorum. Founded ca. A.D. 78 at the time of Agricola's Welsh campaign (Tac. Agric. 18); occupied (with intermissions) until ca. 390, after the garrison was withdrawn by Maximus (the Macsen Wledig of the Mabinogi) thereafter appearing as the Seguntienses (Not. Dig. occ. 7.49) in the command of the Comes Illyrici.
The cardinal position of Segontium as the NW outpost of the Welsh military region, as well as the importance of the copper mines of Anglesey and Caernarvonshire, explain its long occupation. The fort, terminus of an Antonine Itinerary route, occupies the top of a rounded hill above the tidal mouth of the Seiont (and the famous Edwardian castle adjacent to it); it was excavated mainly in 1920-23. The much reduced circuit of the walls and three of the four double gateways are visible; inside, part of the latera praetorii (headquarters with underground strongroom in the sacellum and added tabularium, with hypocaust; commandant's house; workshops) and six centurial barracks and a forage store in the retentura, all arranged per scamnum. Outside, a Mithraeum (built over) was excavated, and near the cliff above the river are the remains of a large walled compound. The museum at the site is a branch of the National Museum of Wales (Cardiff).
BIBLIOGRAPHYR.E.M. Wheeler, Segontium and the Roman Occupation of Wales (1923-24) MPI; O. Cuntz, ed., Itineraria Romana (1929-) 73-74; G. C. Boon, “A Temple of Mithras . . . ,” Archaeologia Cambrensis (1960) MPI; id., Segontium Roman Fort (1963) MPI; id. in V. E. Nash-Williams, The Roman Frontier in Wales, ed. M. G. Jarrett (1969) MPI; id., Amgueddfa: Bulletin of the National Museum of Wales 18 (1974).
G. C. BOON