Castle...Gate & wall, actually, 3 meters thick riddled with spiral staircases, arrow slots, hallways & rooms.  Was blown to heck with gunpowder in 1694, they left the remainder, which is just beginning to be reclaimed by nature.  All the interesting & fun bits were gated off.  Harumph.

The Church of St. Mary Magdalene was just creepy. Eroded, mossy stonework with the faces of its figures being blown into obscurity.  

The first trip over we got a flat coming into Nottingham.  This wouldn't have been a problem except the tire was rusted on, & we eventually ended up calling Green Flag, where a healthy young man just yanked the thing off-something I'd been afraid to do for fear of damaging the wheel.