Blair Castle.
Blair Castle's tale was the the last real owner had reached the end of his life without any immediate kin. So he instructed his lawyers to track down his nearest living relative and give his estate to them. After his death they spent a fair bit of time looking into this and last tracked down his nearest surving relative - an eighteen year old kid pumping gas in the states. Unsurprisingly, the young man was fairly surprised to see lawyers rock up to him at work and announce that they would like him to come to Scotland to inspect the estate that his great-great-great uncle, however many times removed, had just left him.

Now most people would see owning a castle in Scotland as a) just damn cool and b) a great pickup line in bars. However, this young guy was less than impressed with Scottish weather and thus turned over the castle to the National Trust for a fair amount of money instead.