Harrison was also involved in the building of a series of monuments. His first commission was to design the Jubilee Tower on the summit of Moel Famau, the highest point of the Clwydian Range in North Wales, to celebrate the Golden Jubilee of George III in 1810. This consisted of an obelisk in two stages on a broad base. The obelisk collapsed in 1862, and the base was remodelled in 1970 to make a viewing platform. The design of Lord Hill's Column in Shrewsbury, Shropshire, has been attributed to Harrison, but this is incorrect. The architect was Edward Haycock, but Harrison did make alterations to the design, changing the style of the column, and adding a pedestal with statues of lions; and Harrison did supervise the construction. Harrison designed The Marquess of Anglesey's Column in Llanfairpwll on Anglesey to commemorate the feats of Henry Paget, 1st Marquess of Anglesey. This was constructed in 1816-17 at a cost of nearly £2,000 (). His last memorial was a ceremonial gateway, the Admiralty Arch, at Holyhead, also on Anglesey, to commemorate the landing there of George IV in 1821. It consists of an archway with Doric columns, and cost £600 (), and was opened in 1824.