An Iron Age hillfort on the summit of Holyhead mountain in Anglesey. The forts good natural position meant it scarcely needed any additional defences but it nevertheless has a large stone rampart (defensive wall) on the north and east sides - which has survived to a height of 3m in places. The area enclosed is about 7ha.

The site is also well defended by the rocky terrain surrounding the entrance, which is at the north-east corner. The fort's defences have been broken down, perhaps by the Romans who subsequently used the site for a Roman watchtower intended to provide advance warning of Irish sea raiders. From here signals would have been sent by semaphore via a series of signal towers to the Roman legionary fortress at Chester. The base of the watchtower is still visible today. Managed by Cadw.

Directions

From Holyhead town centre, follow the road to Outer Harbour, then follow signs to South Stack (4.75km). From café car park, follow track to summit.