Jonathan's journey takes him to the Glasgow School of Art, built from 1897 by artist Charles Rennie Mackintosh. The school is considered to be one of Britain's most controversial, challenging and celebrated buildings. With unprecedented access, Jonathan, aided by top climber Lucy Creamer, scales the school to reveal the myriad of influences, from medieval castles to Japanese heraldry, that Mackintosh used to create his modernist masterpiece. On his architectural treasure hunt, Jonathan scales over 90 feet to reveal how the building is modelled on a baronial castle, and how Mackintosh pokes fun at traditional architecture. He also investigates how nature and the Industrial Revolution combine when he explores one of the greatest rooms in Europe - the Mackintosh Library.