Bolingbroke Castle, Moat Lane, Bolingbroke, Lincolnshire
This castle was founded in 1220-1230 by Randulph de Blundevill, Earl of Chester and Lincoln. It was extended and altered in the 14th century when it became part of the Duchy of Lancaster. It withstood a siege during the Civil War in 1643, after which it was slighted, deserted and fell into ruin. The castle was the birthplace of Henry Bolingbroke, the son of John of Gaunt and later Henry IV, in 1367. It was excavated between 1965 and 1973. This site is now in the care of English Heritage (2010).