FamilySearch maps

GENUKI – Genealogy UK and Ireland

David Rumsey Map Collection – great map resource. Best if you use the advanced search

British Ceremonial and Historic Counties Maps – useful for zooming in and finding the exact historic county boundaries – particularly useful for London which was formerly divided into different counties.

National Library of Scotland Side by Side Maps

Registration Districts in England & Wales (1888)

Yorkshire wapentakes – the wapentake is the Danelaw equivalent of the Anglo-Saxon hundred.