Built by William FitzOsbern, 1st Earl of Hereford, the castle builder, in around 1067 to 1071 and shares some similarities with Chepstow Castle, another of FitzOsbern’s designs further south on the River Wye in Monmouthshire.
Initially Monmouth was simply a fairly typical border castle in the Welsh Marches presided over by a Marcher Lord and similar in style and status to its neighbours Grosmont Castle, Skenfrith Castle, White Castle (Wales) or Abergavenny Castle.