Caer y Twr, Holyhead Mountain Watch Tower (c) Eric Jones
Caer y Twr, Holyhead Mountain Watch Tower

Caer y Twr is a late Roman watchtower built within the remains of an Iron Age hill fort on the east slope of Holyhead Mountain.

Holyhead Mountain is the highest hill on Anglesey (calling it a mountain is really stretching things a bit!) and the watch tower would have afforded wonderful views over the Roman harbour of Holyhead to the east.

The remains are now very scant, but the walls of the fort can still be traced. Sections of the perimeter rampart stand to 3 metres. Stones found during excavations of the tower footings suggest that it was built between the 2nd and 4th century AD.

On the west slope of the mountain, below Caer y Twr, is a sizeable hut circle settlement which may have been in use at the same time as the fort.