Dude, I grew up there. It’s “well preserved” in the sense that there’s a small park with a raised central monument (a little wall about 18” high, circular, about 20’ across, At the center of the park, filled with earth). There are roses on top.
There is no hint of castle, medieval or otherwise, the land is flat (apart from the central bit) and it has houses all around. You’d never tell the difference between it and any other park. When they say “preserved” I can only think they mean in the sense that with ground-penetrating radar they can figure out that something was there...
It’s a 10 minute walk from my parents house (“Castlegate Grove”) to this little park. I know because I walked the dog to and from it twice a day for almost a decade.