Llanmelin is an ancient hillfort located in southeast Wales, in Monmouthshire.
Llanmelin Hillfort is situated on a prominent hill called Mynydd Llanmelin, which is part of the Wentwood Hills. The site is relatively close to the border of England.
Llanmelin Hillfort dates back to the Iron Age, specifically to the Late Iron Age period, which is roughly estimated to be between 300 BC and 43 AD. It is believed that the hillfort was constructed and occupied by the native Celtic people of the area, likely as a defensive settlement.
Barber and Pykitt seeks to link it with Camelot, suggesting it was the Caer Calemion mentioned by Nennius.
Source
Historia Brittonum | Probably Nennius, early 9th century