Tickhill Castle, near Doncaster, opens to the public for just one day in June each year. The 11th-century gatehouse and curtain wall hide extensive grounds and a large motte where a medieval keep once stood. The manor is now a 17th-century house rented out to tenants by the Duchy of Lancaster - an estate owned by the Queen. The original timber castle on the site was built by a Norman lord, and it was besieged by King Henry I when a subsequent owner sided with a rival claimant to the English throne. The Crown took ownership and built the curtain wall and gatehouse that can still be seen today. An eleven-sided stone keep was later built on the mound, and the foundations are still visible. King John added a barbican. It was attacked against during a rebellion in 1322, and by 1362 became part of the Duchy of Lancaster, which is held by the reigning monarch. The fortifications began to fall into ruin, and in 1614 the Hansby family leased the site, building the current house where the Great Hall once stood. They supported the Royalists during the Civil War, and the castle became a garrison again. They were forced to surrender when Parliamentary forces attacked Tickhill. The castle's defences were then destroyed by order - parts of the curtain wall were pulled down and the keep demolished. The house remained, and was remodelled in the 18th century, when more sections of the curtain wall were removed to improve the views. The grounds were landscaped and a footpath around the perimeter was added.