Holyhead Breakwater is situated at the north-western end of Holyhead in Anglesey in North Wales. The Victorian structure, which is 1.7 miles (2.7 km) long, is the longest breakwater in the United Kingdom. The breakwater, which is accessible in good weather, has a promenade on top which leads out to the Holyhead Breakwater Lighthouse.

Holyhead is the largest town and a community in the county of Isle of Anglesey, Wales, with a population of 13,659 at the 2011 census.. Holyhead is on Holy Island, bounded by the Irish Sea to the north, and is separated from Anglesey island by the narrow Cymyran Strait and was originally connected to Anglesey via the Four Mile Bridge.