Scotland. 1998) The Other Orkney Book - Gordon Thomson, (Northabout Publishing. 1980) "The Knap of Howar and the Origins of Geometry" - by Nicholas Cope & Keith Critchlow (Kairos publications 2016). - www.ncope.co.uk External links Orkneyjar - The Knap o' Howar Knap of Howar, Papa Westray. 4th-millennium BC architecture in Scotland Archaeological sites in Orkney Prehistoric Orkney Scheduled monuments in Scotland Stone Age sites in Scotland Neolithic settlements Former populated places in Scotland Neolithic Scotland Historic Scotland properties in Orkney Houses in Orkney Papa Westray