A county in Wales, UK, bounded by the rivers Wye, Rumney, Monnow and the Clydach Gorge.
Adjacent counties are: to the east Gloucestershire, north-west Brecknockshire, north-east Herefordshire and west Glamorganshire.

Principal towns include: Newport, Abergavenny, Chepstow, Pontypool, Newbridge, Blackwood and Ebbw Vale.

For many years Monmouthshire was thought to be part of England, however this misunderstanding stemmed from the fact that as Wales consisted of 13 counties and that number is hard to divide up evenly for court purposes, Monmouthshire was included in the Oxford circuit.