Pen Llystyn was an auxiliary fort in north-west Wales, situated in the Dwyfor valley at the base of the Lleyn peninsula, on the road linking Segontium (Caernarfon) with Tomen-y-Mur. The earth-and-timber fort, covering c. 1.8 ha, was built in the Flavian period (probably c. AD 77–78 under Agricola's governorship) as part of the consolidation of north Wales, and appears to have been deliberately dismantled and abandoned within roughly a decade, around AD 86–90, when garrisons were withdrawn for Domitian's Danubian campaigns. A smaller fortlet was subsequently constructed within the site.
Source: Pleiades — A Community-Built Gazetteer and Graph of Ancient Places. View the Pleiades record →
The fort formed a key link in the Flavian military network controlling the Ordovices and policing the western seaboard of Snowdonia, garrisoning a cohors quingenaria of around 500 auxiliaries. Its short occupation makes it a particularly clean exemplar of a Flavian auxiliary fort, undisturbed by later Roman rebuilding.
Rescue excavations by A. H. A. Hogg in 1957 ahead of gravel quarrying recovered an unusually complete plan of the timber buildings, including the principia, praetorium, granaries, ten barrack blocks, and a hospital or workshop, together with the four gates and defences — making it one of the most fully planned timber auxiliary forts in
Pen Llystyn was an auxiliary fort in north-west Wales, situated in the Dwyfor valley at the base of the Lleyn peninsula, on the road linking Segontium (Caernarfon) with Tomen-y-Mur. It is recorded in the Pleiades gazetteer of ancient places as a fort site from the Roman period in Britain.
Pen Llystyn is classified as a Roman fort — a military site in the Pleiades ancient world gazetteer. Roman Britain's archaeology encompasses thousands of sites ranging from legionary fortresses and marching camps to villas, temples and towns.
Several Roman sites lie within a short distance, including Segontium: Roman Bath House (17.4 km), Segontium (17.4 km), Mithraeum at Segontium (17.4 km). Aubrey Research maps over 2,200 Roman sites across Britain, drawn from the Pleiades ancient world gazetteer.
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