Tomen y Mur Roman Fort

According to Tacitus, the native Celtic tribe of Ordovices aggressively resisted Roman occupation of their territory in central and Northwest Wales. Alongside the Silures, they fought a bitter guerrilla war under the leadership of Caratacus during the AD 50s. Shortly before Agricola's governorship began in AD 78, the Ordovices were still actively resisting and had massacred an entire regiment of Roman Cavalry based in their territory. Agricola's response – part of his overall conquest of Wales – was so brutal that Tacitus tells us that the Ordovices were effectively wiped out.

Tomen y Mur was probably built to maintain Roman authority over the area following Agricola's campaigns. Its purpose was to oversee the local populations and protect road communications. The fort, which was first built from raised earthworks and timber, probably housed a cavalry unit of 1000 mounted troops. In the early 2nd century, the fort's personnel was reduced in size and rebuilt in stone to accommodate 500 infantry.

Inscribed stones, found at Harlech Castle and believed to be from Tomen y Mur, document the rebuilding of the fort in stone. Each stone commemorates, in paces, various lengths of completed fortress wall and the units (Centuria) who built them. Some of these Centurial Stones were on display at the now closed Segontium museum, Caernarfon. A section of the 2nd-century curtain wall has recently been reconstructed to give an impression of how the defences may once have looked.