The current structure was commissioned as the county prison to replace an earlier
gaol on the site which had been designed by
Joseph Turner and completed in 1793. The new building, which was designed in the
Gothic style, was completed in 1869. The site incorporated a
medieval tower (known as the Hanging Tower) that once formed part of the
town walls. The last execution in the prison, the hanging of the labourer, William Murphy, for the murder of his girlfriend, Gwen Ellen Jones, was carried out by
Henry Pierrepoint at the Hanging Tower on 15 February 1910. The building closed as a prison in 1921 and was subsequently converted to create additional offices for
Caernarvonshire County Council which was based immediately to the south in the old
County Hall. A tower with an archway for vehicles, displaying the brightly painted new
coat of arms of Gwynedd County Council and topped with a
mansard roof, was subsequently erected at the north end of the long north-south prison block; this created a link, at first floor level, with the office facilities in Gwylfa. A modern office block providing additional facilities was built between Castle Street and Shirehall Street in the 1980s. On 1 April 1996, following implementation of the
Local Government (Wales) Act 1994, the complex became the local seat of government for the new local authority in the area,
Gwynedd Council. ==References==