HMP Castle Huntly is a 600-year old castle that was once the seat of the Bowes-Lyons. The earliest part of castle is a mid-15th century L-plan tower house built on a steep rocky outcrop above the Carse of Gowrie. It evolved during the 17th and 18th centuries through various alterations and extensions with the most dramatic change carried out by George Paterson in 1776. This included the crenellation of the Castle, the addition of two Georgian Regency style wings flanking the entrance, and the reconstruction of the roof to include a central round tower and capped corner turrets. Castle Huntly sits within a designed landscape of terraced gardens, avenues and statues, with an ice house and doocot. It was purchased after WWII by the Scottish Prison Service and has been used as a custodial facility ever since.