Richmond Castle, Yorks.

English Heritage
Richmond Castle stands on a rocky promontory above the River Swale, and overlooking the picturesque old town of Richmond. The castle is Norman, and the towering keep is unusually complete. Visitors can climb up inside it for panoramic views over the castle’s great courtyard, the wide cobbled market place of Richmond, and the land beyond. There is an exhibition space, and a garden, its origins contemporary with the castle, on a terrace overlooking the River Swale. Inside the circuit of walls is a broad spread of green, with the vertical lines of the well-preserved keep soaring above.
The castle is well worth a visit if you are touring in the area. The castle is in the town and there is no dedicated parking. It was here that I encountered the parking-disk system used in North Yorkshire, that involves obtaining a free cardboard disk from a shop (etc), setting your time of arrival, and leaving it on view in your car.
The old town itself is also interesting, as I recall.