The Wentworth Castle estate holds a number of monuments and structures, including this sham castle known as Stainborough Castle, on the highest point of the grounds. Finished in 1731, it was built by Thomas Wentworth as a ruined folly and inscribed 'Rebuilt in 1730'. It originally had four towers, named after his four children. Now only two remain. You can climb a (mercifully sturdy, steel) spiral staircase to the top and the views from up there are lovely.
And right at the top, there's a dragon!
It's all rather nice and I could well imagine the household gathering there for picnics and fun, much as visitors do now. You can almost hear the laughter of those four children.