Holyhead Lighthouse Depot was built around 1870 and is located to the west of the main harbour. The former Trinity House site included its own pier, offices, a buoy store, workshop and other outbuildings.
The depot served the local area providing maintenance for lighthouses and buoys.
During the automation process, many local lighthouses were monitored from the lighthouse depot at Holyhead. Those lights monitored included St Bees, Bar Light Float, Trwyn Du, Point Lynas, Skerries, South Stack, Bardsey, St Tudwals, Lynmouth Foreland, Lundy South, Mumbles and Pendeen.
The depot was closed in 1988, and monitoring was transferred to the Trinity House Operational Centre at Harwich.
Some of the buildings are now in use by the Holyhead RNLI which houses their inshore lifeboat.
The first Holyhead Lifeboat was established in 1828 and now houses the Holyhead Maritime Museum.
In 2018 a fire broke out in one of the workshops causing significant damage to the building. Six months earlier, storm Emma had caused damage to the nearby marina.