The burial mounds had the same effect, since I saw them by Newgrange north of Dublin. Cool but not fantastic.
What did get me going was Old Sarum, a one-time castle for William the Conquerer.
This bit of info sets you up...
...and here's a model of how they think the castle and surrounding town looked before everybody moved base to Salisbury, down by the rivers.
The king's forces dug deeper into the ground to make the hill supporting the castle even harder to get up...
...and thick walls like this added to the defenses. I'm glad my buddy, Brad, suggested it.
Then I hit Salisbury Cathedral and made my whole trip worthwhile -- I saw one of the four known copies of the original Magna Carta, signed in 1215 by King John, of Robin Hood fame.
More on all this, later; right now I'm beat from walking so much over the last few days.