Blaenau Gwent is a unitary authority area in eastern South Wales. It has three heavily industrialised valleys, which are the setting for the eight post-medieval scheduled monuments. The uplands have three, possibly four prehistoric monuments, and a medieval site is in the south of the borough. There are 13 scheduled sites in total. The county borough was part of the historic county of Monmouthshire (historic), although shifting boundaries mean Y Domen Fawr round cairn was formerly in Glamorgan.