Monmouth Castle was established between 1067-71. It was partially demolished in 1647 and from 1672 it formed the setting of Great Castle House (NPRN 36568). It became associated with the militia during the nineteenth century.
The surviving remains include a roughly oval enclosure, approximately 90m from east to west by 140m, defined by scarps within which, besides Great Castle House, there survive only the ruins of an eleventh to twelfth century great tower and a thirteenth century hall, both much altered in the later medieval period.
RCAHMW, December 2008