Built by the Normans in 1090, and largely unaltered since the 17th century, Skipton Castle is one of the most complete and best-preserved medieval castles in Britain and still has its original kitchen, great hall, and main bedroom. Following the Battle of Marston Moor during the Civil War, it was the only remaining Royalist stronghold in the north of England, yielding in 1645 only after a three-year siege. So sturdy was the squat little fortification with its rounded battlements (in some places the walls are 12 feet thick) that Oliver Cromwell ordered the removal of the castle roofs. The castle's owner, Lady Anne Clifford, was eventually allowed to replace the roofs thanks to a special Act of Parliament, but only with the stipulation that they not be strong enough to withstand cannon fire. The Act was finally repealed in the 1970s to permit repairs at long last. A yew tree planted in the central Tudor courtyard more than 300 years ago by Lady Anne herself to mark the castle's recovery from its Civil War damage is still flourishing.