Various roundhouse resources from around the UK

http://www.nms.ac.uk/kids/people_of_the_past/celts_and_romans_at_birnie/build_your_own_roundhouse.aspx

http://www.bbc.co.uk/history/interactive/animations/ironage_roundhouse/index.shtml

http://www.britishmuseum.org/explore/online_tours/britain/daily_life_in_iron_age_britain/daily_life_in_iron_age_britain.aspx

http://www.ancienttechnologycentre.co.uk/ironageroundhouse.html

Extensive notes & photos on building a roundhouse
http://www.theroundhouse.org/resources/otherhousesengland.htm