Holyhead Roman Fort was a fortified naval base built to support the Classis Britannica, the British arm of the Roman Navy, who were tasked with the suppression of Irish pirates. A watchtower stood on the summit of the nearby Holyhead mountain providing tactical information to the fort.



The Roman Fort at Holyhead, known in the Welsh language as Caer Gybi, was one of a chain of installations designed to counter acts of piracy and raiding from Ireland. It is possible it operated in conjunction with the nearby fort of Segontium. Its original Latin name is unknown but it was probably constructed in the late third century and was effectively a fortified landing place. Stone ramparts enclosed three sides of the fort with the North and South Walls extending down to the waterfront where the warships of Classis Britannica would have been beached. The walls of the fort still stand to an impressive height - over 4 metres tall - and are constructed in the distinctly Roman herring-bone style with courses of flat stone cementing the structure. The wall would originally have been topped with a parapet walk. Round towers were constructed in each of the four corners (although evidence for the one in the South East is limited) and a fighting ditch surrounded the entire site. Today this ditch has gone and the towers have been heavily modified. However, the fort is a rare example of a three walled Roman military installation. Even other third century Roman Saxon Shore forts, which would have had a similar function to that at Holyhead, were complete enclosures.


The fort was primarily a small naval base providing secure shore accommodation for the crews of the ships based there plus storerooms and supporting infrastructure. However its location on the waterfront inevitably meant a limited view for its garrison. To compensate a small watchtower was constructed on the summit of the nearby mountain providing the fort with tactical awareness of all movements in the surrounding waters. The watchtower may well also have served as a lighthouse providing a navigational beacon for ships at sea.


The fort was abandoned around AD 390 when military forces were largely withdrawn from Britannia. The use of the site in the centuries that followed is sketchy but in the sixth century it was given to St Cybi. He was the cousin of St David and is said to have been the son of Salomon, King of Cornwall. He had declined the crown himself and travelled preaching the gospel until settling on Anglesey. He established a monastery within the former fort's walls and was buried there when he died on 8 November 555. The monastery is now gone but the medieval church of St Cybi still occupies the site.




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What's There?

Holyhead Roman Fort is a rare surviving example of a three side Roman fortification. The third century walls survive to an impressive height although, due to reclaimed land, the fort is now displaced from the coastline. The foundations of an associated watchtower can be found on Holyhead mountain which, on a clear day, offers superb views over the Irish Sea.

Holyhead Roman Fort Layout. The layout consisted of a wall on three sides protected by a ditch. The wall extended down the cliff to protect the beaching area.

Roman Walls. The walls of the fort survive to an impressive height.

St Cybi Church. A monastery was established within the fort's walls in the sixth century AD. This has long since gone but a medieval church dedicated to St Cybi, still occupies the site.

Round Towers. A round tower was constructed on the two corners and at the points where the curtain wall descended onto the beach.

Interior. The interior of the fort.

Roman Watchtower. The tower provided a clear all-round view of the surrounding sea enabling vessel movements to be monitored and reported back to the fort.

View from the Roman Watchtower

Getting There

Neither Holyhead Roman Fort nor the watchtower are sign-posted but both are reasonably easy to find. The fort itself is located off Victoria Road and there is a car park directly adjacent (accessed via Swift Square). The watchtower is found with Breakwater Country Park. There is a dedicated car park for visitors and a clear path to the top of Holyhead mountain.

Holyhead Roman Fort

LL65 1BU

53.311775N 4.632319W

Car Park (Breakwater Country Park)

LL65 1GY

53.316439N 4.664617W

Holyhead Roman Watchtower

No Postcode

53.319524N 4.673906W