Gazetteer of Markets and Fairs
Gazetteer of Markets and Fairs in England and Wales to 1516

National Gazetteer of Wales
Place name index, map of Wales, Counties of Wales, administrative Wales

Old-maps.co.uk
A digital historical map archive for Britain

Ordnance Survey
Introduction to Welsh origins of place names in Britain

Tom's Big Chest of Old Welsh Maps
Welsh county maps by Samuel Lewis and published in 1833