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 Mail Pier Light Holyhead Mail Pier Light Holyhead Mail Pier Light on Salt Island, Anglesey, is an inactive lighthouse which was built by the civil engineer John Rennie in 1821. It is probably the second oldest lighthouse in Wales, after Point of Ayr Lighthouse and is the last of three lighthouses located on the island. There is a matching tower in Howth, Ireland, also designed by Rennie, for the other terminal of the Irish packet steamer. The lighthouse is of national significance as one of John Rennie's surviving works. He was one of the most eminent engineers of the world's first Industrial Revolution.