Abergavenny , meaning Mouth of the River Gavenny, is a market town in Monmouthshire, Wales. It is located 15 miles (24 km) west of Monmouth on the A40 and A465 roads, 6 miles (10 km) from the English border. Originally the site of a Roman fort, Gobannium, it became a medieval walled town within the Welsh Marches. The town contains the remains of a medieval stone castle built soon after the Norman conquest of Wales.