I've been thinking about this and lincoln castle is meant to be an iron age fort [although late bronze age pots have been found in the lawn right next to the castle], so this may make the origins of the castle late bronze age, so i suppose technically this is the first prehistric site i visited, this is a lot harder than i though, it started off as hetty peger's tump and nympsfield, then became carnac [ even though i was young and never got out the van ] and now it's suddenly become my home town castle because it is supposed to be built on an iron age fort with a late bronze age site right next to it, sorry to everyone for what i thought was an easy question but clearly isn't as easy a question as i thought it was!!!