Segontium Roman fort remains, Caernarfon

Segontium Roman fort remains, Caernarfon

Here the A4085 road runs across the site of a Roman auxiliary fort, which was named Segontium after the nearby river Seiont. Most of the site is to the north, past the museum – follow the link below for visiting information.

Segontium was probably the Romans’ largest fort in North Wales. It was founded in 77AD after Agricola, governor of Roman Britain, quelled a rebellion by the local Ordovician tribe.

The fort was initially made of wood and earth, and gradually upgraded using stone in the 2nd century. There were four gateways. The barracks could accommodate 1,000 infantrymen.

Some of the barracks were demolished in the 2nd century. Newer buildings in their place included a large house and a baths building. This may reflect the fort’s evolving role as an administrative centre for mining of the region’s rich mineral deposits, along with defending the coast from pirates and raiders..

Many Roman objects have been found at the site. The most recent coins show that soldiers were based at Segontium until 394. It was used for a longer time than any other Roman fort in Wales.

A settlement grew up outside the fort. Remains of a temple dedicated to Mithras were excavated c.150 metres east of the fort. A similar distance to the west was a smaller fort, often referred to as Henwalia (old walls). Its surviving western wall is close to the river, and it may have been associated with the Roman port nearby.

St Peblig’s Church, east of Segontium, is named after Publicius, son of Magnus Maximus and a Welsh chieftain’s daughter, Helen. How the couple met – after Magnus saw Helen in a dream – is told in the ancient Mabinogion legends. Magnus ruled the western Roman empire from 383 to 388. Items found in the churchyard indicate that it occupies the site of a Roman cemetery.

Stones from Segontium were used to build Caernarfon’s medieval castle, but extensive foundations remain.

With thanks to Gwynedd Archaeological Trust and to KF Banholzer, author of ‘Old Caernarfon - Outside the Town Walls’

Postcode: LL55 2LN    View Location Map

Segontium visiting information – Cadw website