Definitely Castile, since you are asking for which castle...
Here's a list of nations with a female ruler name with weight at least 10: (the numbers in parentheses are the total weight of said females. I made a mistake in only adding up those with 10 or more, though)
Ahmadnagar(10), Alencon(10), Armagnac(10), Athens(10), Austria(15), Auvergne(50),
Bar(20), Berry(15), Bijapur(10), Blambangan(25), Bourbonnais(10), Brabant(15), Brazil(25),
Brittany(20), Burgundy(10), Byzantine(60), Caddo(10), Castille(20), Champagne(15),
Chanda(10), Croatia(15), Cyprus(15), Dali/Lanfang/Miao/Yi(100), Dauphine(10), Denmark(20),
EastFrisia(10), England(50), Etruria(40), Flanders(15), Georgia(20),
Gondwana(20), Gotland(60), GreatBritain(15), Greece(10), Gwalior(10), Hainaut(15),
Holland(15), Hungary(10), Imereti(20), Japan(30), Jerusalem(10), Kangra(10),
Keladi(60), Kochin(10), Kutai(25), Lorraine(15), Luxembourg(15),
Madurai(20), Majapahit(25), Marathas(10), Morea(10), Naples(15), Navarra(40),
Nepal(10), Nevers(20), Norway(10), Orleans(10), Parma(25), Patiala(10), Perm(45),
Portugal(10), Achaia(15), Punjab(10), Russia(50), Scandinavia(40),
Scotland(10), Sicily(15), Spain(45), Sunda(25), Swahili(20),
Sweden(20), Tirhut(10), Toulouse(15), Urbino(40), Venad(30)