Scarborough Castle stands on a massive promontory of rock that rises sheer-sided high above the North Sea. The 12th-century great tower crowning it is the centrepiece of a royal castle begun by Henry II, which was strengthened by later monarchs. It played a prominent part in national events during the Middle Ages, and was twice besieged during the English Civil War. But the castle buildings are relatively modern additions to a site which, as a natural fortress, has been intermittently inhabited and fortified for nearly 3,000 years.