Torfaen is a county borough in the south-east of Wales. Torfaen is bordered by the county of Monmouthshire to the east, the city of Newport to the south, and the county boroughs of Caerphilly and Blaenau Gwent to the south-west and north-west. It is within the boundaries of the historic county of Monmouthshire, and between 1974 and 1996 was a district of Gwent, until it was reconstituted as a principal area in 1996.

Monmouthshire is a county in the south east of Wales. It borders Powys to the north; the English counties of Herefordshire and Gloucestershire to the north and east; the Severn Estuary to the south, and Torfaen, Newport and Blaenau Gwent to the west. The largest town is Abergavenny, and the administrative centre is Usk.