Lincoln castle was erected 1066-68 by William The Conquerer (not on his own) to defend the City against his many enemies. The castle still stands today, housing the City's Crown Court and one of the three remaining original copies of the Magna Carta.
Again, most of that rubbish is discounted by the locals who are fully aware of the FACT that the castle was erected by Baron Curfew in order to defend his own palace housed a few yards up the road. The castle to this day is home to an original copy of 'Around The Houses' by Baron Curfew, written in it's original Latin form.