And of course you'll need a retinue to man the walls.
[1] https://en.wikipedia.org/wiki/The_Three_Musketeers#Plot_summ...
I always misread it as Underzo when I was a kid though.
The price of repairs are also mind-boggling, but for those you can get state subsidies
But, yes, I'm sure maintenance is in the $100K+ a year area easily.
Basically it's only pleasant in the summer or if you're being raided by a neighbouring state.
This castle is from the 11th century. It might have had the 11th century equivalent, which was feudal burdens, but those have almost certainly been abolished since the revolution.
Scotland has formally abolished the feudal system; England, however, has not, so you may still find yourself liable for the repair of a church built ten centuries ago. https://en.wikipedia.org/wiki/Chancel_repair_liability