Location and coordinates are for the approximate centre of Oldcastle within this administrative area. Geographic features and populated places may cross administrative borders.
Gazetteer of the British Isles (Edinburgh: Bartholomew, 1887). John Bartholomew
Oldcastle, par., Monmouthshire, on river Monnow, at boundary with Herefordshire, 7 miles NE. of Abergavenny, 934 ac., pop. 50.