Great Castle House is a former town house built on the site of part of Monmouth Castle in Wales. Amongst the town's most significant buildings, it has a Grade I listing and is one of 24 sites on the Monmouth Heritage Trail. The house is located on Castle Hill, off Agincourt Square in Monmouth town centre.

Monmouth Castle is a castle close to the centre of the town of Monmouth, the county town of Monmouthshire, on a hill above the River Monnow in south-east Wales.