Newcastle (Welsh: Castell-newydd) is a small village in Monmouthshire, south east Wales, United Kingdom.

Its history is obscure, but it is believed to have been founded by Hugh de Lacy, lord of Ewyas in the 12th century, and in the reign of Edward III it belonged to the Huntley family.

[2] Pool Farm, nearby, is described as "one of the most completely surviving cruck-trussed hall houses in the county",[2] and is a Grade II listed building.

[3] About 1 mile (1.6 km) north of the village is the Victorian Palladian mansion of Hilston Park, now used as an outdoor education centre.

[5] Another botanical highlight in the village was a wisteria which was one of the oldest examples of this plant in Britain and grew on the inn in the village which was renamed as the "Wellington Arms" after the Battle of Waterloo in 1815 when the wisteria was 150 years old.