Castle, built in circa 1220-30 and enlarge in C14. It was twice rebuilt in the C15 and C16. It withstood a siege during the Civil War in 1643, after which it was sleighted, deserted and fell into ruin, now visible only as a series of earthworks and ruins. It was excavated between 1965 and 1973. The castle was of compact enclosure design complete with a large gatehouse, round towers and a moat. Today the castle is a ruin with only the ground floors of the towers remaining and the lower parts of the walls. Squared greenstone rubble, ashlar dressings. Courtyard plan with octagonal and round corner towers. Walls stand to about 6'0". Built by Randulph de Blundeville, the Earl of Lincoln, became the home of the powerful John of Gaunt in C14 and was the birthplace of his son, Henry Bolingbroke, who later became King Henry IV. Brown writes held 1154-98 by Roumare (sometime earl Lincoln) 1198 on held by Blundeville earl Chester. The strange earthwork by the castle has been described as fishponds in the past but probably represents a Civil War fort.