Anglesey the island. The highest six are Holyhead Mountain, ; Mynydd Bodafon, ; Mynydd Llaneilian, ; Mynydd y Garn, ; Bwrdd Arthur, ; and Mynydd Llwydiarth, . To the south and south-east the island is separated from the Welsh mainland by the Menai Strait, which at its narrowest point is about wide. In all other directions the island is surrounded by the Irish Sea. It is the 51st largest island in Europe, and just five square kilometres smaller than Singapore. There are several small towns scattered around the island, making it quite evenly populated. The largest are Holyhead, Llangefni, Benllech, Menai
Holyhead Mountain Bodafon Mountain () on the main island. On the east side of the mountain is the site of a late Roman watchtower called "Caer y Tŵr" (Tower Fortress), from which Holyhead Mountain's Welsh name is derived. Holyhead Mountain also has an Iron Age stone circle settlement near its foot. This shows evidence of being occupied in the middle part of the Stone Age, the Neolithic Age, the Bronze Age and the Iron Age. There are traces of field systems and the bases of dry-stone walls of twenty huts, and there are a number of standing stones in the vicinity. The