[2][3] The original design involved the right-hand part of the present central block, facing south towards Bangor Cathedral, and the east wing, which was projected forward.

A slate plaque was installed reading: "Dominus Gulielimus Episcopus Aedificavit AD - 1810" (English: The home of Bishop William erected in the year of our lord 1810).

[4] After the borough council was reformed under the Municipal Corporations Act 1883,[5] the new civic leaders decided to acquire the building and to convert it for use as its headquarters in 1903.

[6] Internally, the principal new room established was the council chamber, which featured a vaulted ceiling, on the first floor.

[10] In March 2014, an extensive programme of refurbishment works costing £2.6 million was initiated, with support from the National Lottery Heritage Fund, to convert the building into a museum.