Grosmont Castle (historically also spelled Grisemount and Grisemond) is a ruined castle in Grosmont, Monmouthshire, Wales, very near the border with Herefordshire, England, and overlooking a bend in the River Monnow. It is generally considered to have been largely built by Hubert de Burgh early in the 13th century, on an earlier Norman foundation, but was extended in the 14th century.