When I was a kid, there was a playpark in Freshbrook that had a wooden fort. It was great. I have no idea whether it is still there.
Sadly, it did not have a moat though.
When I was a kid, we used to go and have pop and crisps at some boozer with a massive pub garden which had a crows nest in it. We spent days at this place in the summer. I have no idea where it was but I grew up around the Cirencester area.