... is in Gloucestershire. It was reconstructed by the Berkeley family in the 12th century, and has been in their possession ever since (except for a period of royal ownership by the Tudors). No other castle in England has been in continuous private ownership for a longer period. (Windsor Castle and the Tower of London make it the third–longest occupied of all.)
The story of Edward II's murder is shrouded in mystery; some claim that he had escaped and someone else was murdered in his place. But the popular stories of his disembowelment with a red hot poker persist.
Berkeley's other claim to fame (apart from its castle ... oh, and its nuclear power station) is that it's where Edward Jenner carried out Western Europe's first successful vaccination against smallpox.
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