The Gatehouse
- Philip Davis provides a comprehensive listing with bibliography of the medieval castles, castle sites, fortified houses, urban and coastal defences and other fortifications of England and Wales built or in use from 1000 to 1600. He also gives a list of li
- http://www.ecastles.co.uk/philipdavis/

British Castles, Stately Homes and Houses
- An interactive map leads to short descriptions by Risto Hurmalainen of castles and historic buildings he has visited, a gallery of expandable thumbnail photographs and links to official sites.
- http://koti.welho.com/rhurmal1/linnat2004/castles.html

Anglo-Norman Castles
- Illustrated articles by Paul Martin Remfry, along with details of his booklets on castles in England and Wales.
- http://www.castles99.ukprint.com/

UK Castles
- A browsable directory of mainly medieval UK castles, arranged by country, county, and A-Z.
- http://www.uk-castles.co.uk

Castles Castles
- Andy Catling provides an overview of the history of medieval castles and the society that built them plus a comparison with Victorian mock castles - accompanied by photographs.
- http://www.castles-castles.com

Castles, Palaces and Stately Homes of Britain
- A guide with many photographs, to some of the castles, and stately homes of Britain, with particular emphasis on Nottinghamshire, where the author comes from.
- http://louisabrown.net/Castles.htm

Castle Studies Group
- Aims to promote the study of castles in all their forms and by all possible means. Contains committee information, events, conference, news and publications.
- http://www.castlestudiesgroup.org.uk/

The Good Castle Guide
- A gazetteer by Nigel Bacon of over 1600 fortified sites in the British Isles ranging from prehistoric and roman forts through medieval castles to 19th century martello towers.
- http://web.ukonline.co.uk/nigel.bacon/

CastleUK.net
- Site provides information and pictures for many castles in England, Scotland and Wales. Visitor information is enhanced by use of ordnance survey maps to pinpoint actual locations. Castles are easily searchable by location or alphabetical listings.
- http://www.castleuk.net/

Island Castles
- Appealing introduction to medieval fortresses of Great Britain by Edward Blanchard, from The War Times Journal, with professional photographs of a few of the most famous.
- http://www.wtj.com/articles/castles/

CastleXplorer
- Uses interactive maps to find castles in Great Britain, featuring descriptions, photos and directions.
- http://www.castlexplorer.co.uk/

Castles and Fortifications of England and Wales
- Database of 800 survivals. Interactive maps lead to photographs, brief descriptions and visitor information by Charles Taylor. Also a brief, illustrated history of the subject.
- http://www.ecastles.co.uk/

Castles of Britain
- US-based Castles Unlimited offers a commercial research service. Lists of castles; photo gallery; ground plans and bird's-eye views of a few castles; general background articles; glossary.
- http://www.castles-of-britain.com/