
The Wikipedia article mentions that the builder, Michael Rubel, purchased the Glendora property in 1959. It doesn't point out that he was only 19 years old at the time. He and his mother worked out the deal and moved into the existing citrus packing house with their family antiques.
Michael's mother, Dorothy Deuel Rubel, had been a dancer on Broadway in the Greenwich Village Follies and was friends with Sally Rand. (You'll find their memorabilia when you tour the castle.) Dorothy loved to host parties, and many Hollywood glitterers attended.
The castle is another story, to be continued...