Margary numbers are the numbering scheme developed by the historian Ivan Margary to catalogue known and suspected Roman roads in Britain in his 1955 work The Roman Roads of Britain. They remain the standard system used by archaeologists and historians to identify individual Roman roads within Britain. It is not known how the Romans identified the roads they built within Britain, and well-known names such as Watling Street and the Fosse Way largely date from the Anglo-Saxon period, are sometimes ambiguous or duplicated, and cover only a small proportion of the known network.