[2] The new building was designed by the county surveyor for Caernarfonshire, John Thomas, in the Gothic Revival style, built by a local contractor, Richard Williams, in buff brick and was officially opened on 31 August 1875.

[2][3] The opening was celebrated by two concerts, both conducted by Tanymarian, which included performances by the Welsh baritone singer, James Sauvage, in the presence of the local member of parliament, Morgan Lloyd.

[2] The design involved a symmetrical main frontage with five bays facing onto Newry Street; the central bay, which slightly projected forward, featured a deeply recessed arched doorway with a stone surround on the ground floor and a pair of slightly recessed sash windows flanked by colonettes on the first floor.

[2] Following significant growth in the population, largely associated with the status of Holyhead as a seaport, the area became an urban district with the town hall as its headquarters in 1894.

[9] An extensive programme of refurbishment works, which involved the creation of four new offices above the main assembly hall, was completed by DU Construction in April 2007.