A prominent ditch, with traces of a bank, at Clawdd Ddu, extends c.550m but is obscured at either end. It encloses the suburb of Over Monnow, across the Monnow Bridge (Nprn24219) from Monmouth (see Nprn33172), with whose defences (see Nprn33168), this work can be associated.
Excavation in 1966 indicated that the work was of two phases, divided by a layer provisionally dated 1250-1350.
The ditch is maintained as a drainage feature (1958).
(source Os495card; SO51SW37)
RCAHMW AP94-CS 0442