Check out this castle a guy built in Napa Valley.
Castello di Amorosa
He insisted on using traditional 13th century medieval methods and authentic architectural styles. The place even comes complete with an authentic period style dungeon and torture chamber (he spent tens of thousands buying 700 year old authentic period torture devices) also check out the original medieval style artwork he had done in the great hall. The wine cellar is also a vaulted ceiling work of art. Apparently it took 14 years to build and he brought over actual Italian stone masons and insisted they use authentic 13th century stone working techniques to build it as well.
Castello di Amorosa - Wikipedia, the free encyclopedia
The only problem is you'd need a private army to defend the castle walls.
I do like how he made the winery building itself based on a medieval monastery.