Caer Gybi (c) Nigel Mykura
Caer Gybi

The walls are all that survive of Caer Gybi, a small Roman fort dating to the late 3rd century. The fort stands to the west of Holyhead harbour, and was built around 300 AD as a defence against Irish pirates.

Construction of this fort took place at the same time as the Saxon shore forts along the south east coast of England, and was probably part of the same concerted efforts by the Roman elite to retain control of their British possessions.

The church of St Gybi now stands within the perimeter walls, which form three sides of a rectangle; the third side remaining open to the natural harbour.

Some sections of the wall stand to almost 13 feet in height, and it is 5 feet thick in places. The walls were made using herringbone masonry with flat stones used as bonding courses.

The fort originally boasted three corner towers. There are still three towers, but only one of them - the north-west one - is completely original. The total area of the enclosure is just under 1 acre. The site is signposted from the centre of Holyhead, and is easily accessible.