Conisbrough Castle features a distinctive round Norman keep, a rare architectural design unique in England, standing over 90 feet high with massive walls exceeding 15 feet thick and supported by six enormous projecting buttresses. Built by Hamelin Plantagenet, King Henry II's half-brother, in the 1170s or 1180s, the keep represents an architectural gem and one of England's finest examples of late Norman defensive architecture according to historians. The circular design with six buttresses distinguishes it from conventional square Norman towers, while the four interior floors included chambers for both the lord's everyday use and private quarters. Remarkably, Conisbrough escaped damage during the English Civil War, becoming a picturesque ruin that inspired Sir Walter Scott's famous novel Ivanhoe, published in 1819.
