Looking like the ultimate sandcastle you'd see at the beach, this honey-stone edifice atop a hillock was built around 1200. From the 14th to 17th centuries it was home to the Percy family (whose descendants still live at Alnwick Castle), and was pivotal in the Wars of the Roses and the English Civil War. It became a national monument in 1915 but the Duke's Rooms remained under the family's control until 1987. Audio guides give a vivid account of its history.