Anglesey (/ˈæŋ.ɡəl.siː/; Welsh: Ynys Môn [ˈənɨs ˈmoːn]) is an island off the north-west coast of Wales. With an area of 276 square miles (715 km²), Anglesey is by far the largest island in Wales and the seventh largest in the British Isles. Anglesey is also the largest island in the Irish Sea by area, and the second most populous island (after the Isle of Man). The population at the 2011 census was 69,751. Two bridges span the Menai Strait, connecting the island to the mainland: the Menai Suspension Bridge, designed by Thomas Telford in 1826, and the Britannia Bridge.

A historic county of Wales and later administrated as part of Gwynedd, Anglesey today makes up the Isle of Anglesey County along with Holy Island and other smaller islands. The majority of Anglesey's inhabitants are Welsh speakers and Ynys Môn, the Welsh name for the island, is used for the UK Parliament and National Assembly constituencies.

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