Caer Gybi Roman Fort

Northern military outpost in a strategic coastal location

Dating back to the 3rd century, Caer Gybi’s position on low cliffs overlooking the sea suggests it was part of a coastal network of defences, possibly linked to the late Roman watchtower at Caer y Twr on the summit of Holyhead Mountain.

The walls of this rectangular fort are extremely well-preserved, standing up to 13ft/4m high and 5ft/1.5m thick. You can also see remains of four corner towers. Occupying a vantage point above the harbour, the 26ft/7.9m north-east tower is the most prominent, though the top section is a later rebuild possibly dating to the medieval period.