Harrison is considered to have been a leader of Greek Revival architecture in the northwest of England. His major surviving works in this style include the Lyceum in Liverpool, the Portico Library in Manchester, and the Commercial Newsroom in Chester. Most of Harrison's works are in Lancashire and Cheshire, but he also designed buildings in North Wales, and in Shropshire. His only work away from this part of the country was his design for the New Buildings at Magdalen College, Oxford. In Chester, Harrison designed a house for himself, St Martin's Lodge. In addition to domestic and civic buildings, he worked on memorial structures, including the Jubilee Tower on Moel Famau in North Wales, Lord Hill's Column in Shrewsbury, Shropshire, and a memorial gateway in Holyhead, Anglesey. His final major designs were for two bridges in Chester. In 1825-26 he widened the Old Dee Bridge. He then designed a new bridge, the Grosvenor Bridge. This was not completed until after his death in 1829, but it was at the time the largest structure of its type in the world.