Arfon (cantref)

The cantref's position gave it control over the Menai Strait, which has played an important part in Welsh history.

Broadly speaking, it stretched from the peaks of Yr Eifl in the west to Afon Cegin, a stream just east of Bangor, and inland from the shores of the Menai southwards into the heart of Snowdonia (Eryri), including Dyffryn Nantlle and the strategic Llanberis Pass.

The main defensive fortress in the era of the Welsh princes was Dolbadarn Castle, near modern Llanberis.

The bishops of Bangor, the successors of St Deiniol, had an extensive holding of land in the north of the cantref.

Lleu Llaw Gyffes flies to Nantlleu in Arfon in the form of an eagle after his attempted murder by Gronw Pebr.