Visit the remains of a 13th century hexagonal castle, birthplace in 1367 of the future King Henry IV, with adjacent earthworks. Bolingbroke Castle was one of three castles built by Ranulf de Blundeville, Earl of Chester and Lincoln, in the 1220s after his return from the Crusades (the others being Beeston Castle, Cheshire, and Chartley, Staffordshire). After Blundeville’s death, the castle remained in the ownership of the Earls of Lincoln and was later inherited through marriage by John of Gaunt, Duke of Lancaster.