The fortified bridge over the River Monnow (Afon Mynwy) at Monmouth, South Wales. This is one of only two remaining fortified bridges in Great Britain and the only one with the gatehouse actually on the bridge. It dates from the C13th, replacing an earlier wooden construction. In its time it has also served as a gaol, munitions store and principally as a toll gate. It has been considerably restored over the years and, with traffic becoming heavier, was eventually designated as pedestrian only.