Blenheim Palace, a UNESCO Heritage Site in the oddly shaped county of Oxfordshire. The city of Oxford totally deserves this designation, and I have no idea why it doesn’t already have it.
It’s the only palace in Britain that’s privately owned (by His Grace The Duke) and was the birthplace of British wartime prime minister, the incredibly racist and hawkish Sir Winston Churchill. The misogynistic aristocrat also proposed to his wife in the gardens.
A fun place to be, and indeed it’s worth the cost (they also want to lure you back by giving you a complimentary offer to turn your ticket to a one-year one).