Monmouth is a market town and community in Monmouthshire, Wales, situated on where the River Monnow joins the River Wye, two miles f…Monmouth is a market town and community in Monmouthshire, Wales, situated on where the River Monnow joins the River Wye, two miles from the Wales–England border. The population in the 2011 census was 10,508, rising from 8,877 in 2001. Monmouth was the county town of historic Monmouthshire, although Abergavenny is the largest settlement and Monmouthshire County Council has its main offices at Rhadyr, just outside Usk. Monmouth is in the UK Parliament constituency of Monmouthshire and the Senedd constituency of Monmouth.