Hen Gaer is an Iron Age hillfort, on a hill adjacent to and east of Bow Street, Ceredigion, Wales.
Other names of the hillfort are Broncastellan and Caer Shon.
Description Hen Gaer ("Old Castle") is smaller than a typical tribal fortification. It is strongly defended; the single rampart is about wide and above the interior, with a rock-cut external ditch. On the north-east side, carefully laid stone blocks of the original rampart wall can be seen. The main entrance is on the west side. There is a circular mound outside the entrance: it is not an earlier barrow, but may be a defensive feature.Christopher Houlder. Wales: An Archaeological Guide. Faber and Faber, 1978. Page 114.
The enclosed area includes some of the southern hillslope; it is thought this may have been to make the fortification visible from the narrow valley below, at the confluence of Afon Stewi and Nant Seilo forming Afon Clarach.
See also Hillforts in Britain List of Scheduled prehistoric Monuments in Ceredigion
References