Holyhead Breakwater (Morglawdd Caergybi)
| Location | SH 25676 84756 / 53.3309, -4.6193 / gracing.silks.booth |
| Established / Rebuilt / Automated / Closed | 1873 / — / 1961 / — |
| Architect or Builder | John Hawkshaw ? |
| Height of tower (m) / above sea level (m) / Range (NM) | 19 / 21 / 14 |
| Character | Fl(3) G 10s |
| Optic | Electric beacon |
| Owner | Stena Line |
This lighthouse is perched at the end of a 2.75 km long breakwater, the longest in Britain. It is one of three square lighthouses in Wales, the others being Bardsey and Amlwch, all in north-west Wales. It is still operating, exhibiting a flashing green light, and is run by the Holyhead Port Authority.