Built by the Normans in 1190 and largely unaltered since the 17th century, Skipton Castle is a remarkably well-preserved medieval castle. After the Battle of Marston Moor during the Civil War, it remained the only Royalist stronghold in the north of England. So sturdy was the squat little fortification with its rounded battlements (in some places the walls are 12 feet thick) that Oliver Cromwell ordered that the roof be removed, as it had survived one bombardment after another during a three-year siege. After the war the castle's owner, Lady Anne Clifford, asked if she could replace the roof, so Cromwell passed an Act of Parliament to allow her do so, stipulating the roof couldn't be strong enough to withstand cannon fire. The Act was finally repealed in the 1970s in order for the roof to be repaired. In the central courtyard a yew tree planted more than 300 years ago by Lady Anne herself, to mark the castle's recovery from its Civil War damage, is still flourishing.