An ancient borough was a historic unit of lower-tier local government in England and Wales. The ancient boroughs covered only important towns and were established by charters granted at different times by the monarchy. Their history is largely concerned with the origin of such towns and how they gained the right of self-government. Ancient boroughs were reformed by the Municipal Corporations Act 1835, which introduced directly elected corporations and allowed the incorporation of new industrial towns. Municipal boroughs ceased to be used for the purposes of local government in 1974, with borough status retained as an honorific title granted to some post-1974 local government districts by the Crown.

A burh or burg was an Anglo-Saxon fortification or fortified settlement. In the 9th century, raids and invasions by Vikings prompted Alfred the Great to develop a network of burhs and roads to use against such attackers. Some were new constructions; others were situated at the site of Iron Age hillforts or Roman forts and employed materials from the original fortifications. As at Lundenburh, many were also situated on rivers: this facilitated internal lines of supply while aiming to restrict access to the interior of the kingdom for attackers in shallow-draught vessels such as longships.