Penrhos Country Park

Anglesey Aluminium was a joint venture between Rio Tinto and Kaiser Aluminum. Its aluminium smelter, located on the outskirts of Holyhead, was one of the largest employers in North Wales, with 540 staff members, and began to produce aluminium in 1971. It was built on the Penrhos Estate, 500 acres of which were sold by the Stanley family for the project. Up until its closure it produced up to 142,000 tonnes of aluminium every year and was the biggest single user of electricity (255 MW) in the United Kingdom.Alumina and coke shipped from Jamaica and Australia would berth at the company's private jetty in Holyhead harbour. This jetty is linked by a series of conveyor belts passing through tunnels to the plant. A spur rail link from the main North Wales Coast Line runs into the plant and was used for both receipt of raw materials and despatch of aluminium. The plant was powered from the National Grid and received most of its electricity from Wylfa nuclear power station 15 miles away. AA was used as a base load for Wylfa and saved the grid the cost of keeping a power station on standby. The power contract terminated in 2009, and the aluminium smelting operation was shut down as no new contract was negotiated. The aluminium re-melt facility initially remained open after the shut down of the smelter, but its closure was announced in February 2013. The company has announced tentative plans for a biomass plant on the site, but smelting operations have been halted and the plant mothballed until 2016.It was announced in September 2022 that the former Anglesey Aluminium site had been purchased by Stena Line, with their intention to use the site to facilitate an extension of Stena's existing operations of the Port of Holyhead. The sale included the spur rail line, the jetty in Holyhead harbour and the former conveyor tunnel linking the jetty to the main site.Near the smelter the Aluminium Powder Company (ALPOCO) produces aluminium powder, which is used in pastes, pigments, chemicals, metallurgy, refractory, propulsion, pyrotechnics, spray deposition and powder metallurgy. Adjacent to the site is the public access Penrhos Country Park.

Penrhos was a large estate on Holy Island, Anglesey, in north-west Wales.

Ynys Benlas is a small islet situated in the Inland Sea (Welsh: Y Lasinwen), part of the Cymyran Strait between Anglesey and Holy Island. It measures approximately 65 metres (east-west) by 35 metres (north-south) at low tide and covers about 0.2 hectares. Its name translates from the Welsh for "blue top island", which is thought to derive from the fact that bluebells apparently flourished on it. Late nineteenth century Ordnance survey maps refer to the islet as Ynys Henlas, which translates as "old blue island" According to the Archaeological Journal (1844), the islet (referred to as Ben Las in the Journal) may have been an ancient signal hill.

The Stanley Embankment (known locally as the Cob) is a railway, road and cycleway embankment that crosses the Cymyran Strait in Wales, connecting the Island of Anglesey and Holy Island. It carries both the North Wales Coast Line for trains, which runs from Crewe to Holyhead and the A5 road between London and Holyhead. The embankment was designed by, and its construction overseen by, Thomas Telford and was named after the Stanley family who were significant benefactors to the area.Prior to its construction the fastest route to Holyhead from the island's mainland was via the old stone bridge at Four Mile Bridge (Welsh: Pontrhydybont/Pont-rhydbont/Pontrhypont). When the A5 road was being constructed between London and the Port of Holyhead a more direct route was needed. Construction started in 1822 and completed a year later and is a total of 3⁄4 mile (1.2 km) long. It is significantly wider at the base (35 metres) than at the top (10 metres). The embankment to Holy Island was constructed using rock and materials excavated from a site on the Anglesey side. A workers’ hamlet grew up around the artificially-created depression, which was nicknamed “the valley”. After work ended, the settlement remained developing into a medium-sized village known as Valley. A year after opening, the embankment was partly damaged in a storm in 1824.In the 1840s, the embankment was chosen to carry the North Wales Coast Line to the Port of Holyhead (rather than build an entirely new crossing). Work to significantly widen the structure was completed in 1848. To allay concerns that passing trains might startle horse drawn traffic using the embankment, a tall stone dividing wall was built between the road and the railway.The embankment remained the only major crossing between Holy Island and Anglesey for more than 175 years. In 2001 it was superseded by a new wider embankment, which was built as part of the final section of the A55 North Wales Expressway. The section completely bypassed Valley and the old A5 at this point. The new crossing, which carries the modern A55 dual carriageway, was built parallel to the Stanley Embankment, following its north–south alignment.

Cymyran Strait (Welsh: Culfor Cymyran) is a strait that runs from Beddmanarch Bay in the north to Cymyran Bay in the south between the islands of Anglesey (Ynys Môn) and Holy Island (Ynys Cybi). At either end it opens up into the Irish Sea. The strait was first crossed with a permanent land-link by the Four Mile Bridge by the latest date of 1530. It was later crossed by the A5 London to Holyhead Road at Stanley Embankment in 1823, the North Wales Coast Line using the same embankment in 1848, and finally the separate A55 expressway in 2001. The area specifically between the Stanley Embankment and the Four Mile Bridge is often referred to as the Inland Sea (Y Lasinwen) and is almost a lagoon. The only settlement on the shores of the strait is Four Mile Bridge itself, although the town of Holyhead and the villages of Valley and Trearddur are close by.

Beddmanarch–Cymyran is a site of special scientific interest (SSSI) on the Welsh island of Anglesey extending to just over 900 hectares (2,200 acres), and centred on the Cymyran Strait. It was first notified in 1961 for its coastal botanical and ornithological interest. The site is also a marine protected area as it includes intertidal areas and contains marine components.

Trefignath is a Neolithic burial chamber near Trearddur, south of Holyhead on Holy Island, off Anglesey in Wales. In its most complete form it included a large cairn covering three stone tombs, set on a small knoll. It was excavated between 1977 and 1979, revealing several phases of occupation with three separate burial chambers built in succession. It is a scheduled ancient monument, maintained by Cadw. Trefignath is adjacent to an alignment of small standing stones which extends some 350 metres northwestwards. Beyond these, some 450 metres from Trefignath, is the larger Tŷ Mawr Standing Stone.

Ysbyty Penrhos Stanley (English: Penrhos Stanley Hospital) is a health facility in Holyhead, Anglesey, Wales. It is managed by the Betsi Cadwaladr University Health Board.

Holy Island (Welsh: Ynys Gybi, 'the island of (Saint) Cybi') is an island (15.22 sq mi (39.4 km2)) on the western side of the larger Isle of Anglesey, Wales, from which it is separated by the Cymyran Strait. It is called "Holy" because of the high concentration of standing stones, burial chambers, and other religious sites on the small island. The alternative English name of the island is Holyhead Island. According to the 2011 UK Census, the population was 13,659, of which 11,431 (84%) lived in the largest town, Holyhead.

Trearddur or Trearddur Bay (Welsh: Bae Trearddur) is a village, seaside resort and community south of Holyhead on the west coast of Holy Island off the north-west coast of Anglesey in Wales. The community includes the small settlement of Penrhosfeilw and the Refail Farm estate.

Morawelon (Welsh: Môrawelon) is an area and community electoral ward in the town of Holyhead, Anglesey, Wales. In 2011 the ward had a population of 1,504.The Eaton Electrical factory was based in Morawelon from 1961. When its closure was announced, to relocate to Eastern Europe with the loss of 265 jobs, nobody other than the workforce led the fight (unsuccessfully) to keep the factory open. It was to close by December 2009.

Holyhead Mail Pier or Admiralty Pier Lighthouse on Salt Island, Anglesey, is an inactive lighthouse which was designed by the civil engineer John Rennie in 1821. It was built in the early 19th century to help guide shipping into the newly constructed harbour, now known as the Port of Holyhead, which acted as the terminus for the packet service between England and Ireland. It is probably the second oldest lighthouse in Wales, after Point of Ayr Lighthouse and is the last of a series of three lighthouses located on Salt Island.