The relict seawall on Rumney Great Whart comprises a 560 meter length of wall located behing the modern seawall. Much of the surviving structure of clay bank may be original and documentary evidence points to a date as early as 1591 for the setting of the wall. The present height of the wall, on the seawall side is between 1-2 meters and on the landward side it is 3.2 meters. The width at the base measures between 6-7 meters, tapering to 2 meters width at the top. There are three styles of stone revetment at its western end and two modern breaches near its eastern end.

Source: Cadw scheduling description of September 2010