Some have museums and visitor centres, others are unmanned monuments with information boards. Here are the best castles, abbeys, halls and other fascinating places to visit.
1. Byland Abbey
These Cistercian ruins near Coxwold in Ryedale are also the site of a 14th-century battle when King Edward II was caught unawares by Scottish raiders before he fled to York
2. Clifford's Tower
The tower is the remains of what was once the Norman keep of York Castle. A major explosion in 1684 destroyed the defences, and afterwards it was used as a prison until 1929.
3. Fountains Abbey
The jewel in the crown of Yorkshire's abbeys, Fountains was one of the great monasteries of its age. The estate near Ripon is also home to the landscaped Studley Royal water gardens
4. Helmsley Castle
This medieval castle was allowed to decay when the Barons Feversham of Duncombe Park commissioned the building of a grand stately home overlooking the ruins. They still own the castle, but English Heritage maintain it.