Ballaí Dhoire (Derry's Walls) considers the fascinating history of Derry, the last remaining walled city in Ireland. Using specially commissioned CGI, the presenter, Fearghal Mac Uiginn, explores Derry's monastic origins, and reconstructs the manner in which the walls were built 400 years ago. Fearghal identifies the circumstances behind the transition from monastic Derry to the plantation town of Londonderry in 1613, and he considers how the walls have shaped history both within and beyond the walled city itself.