You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: AFRICAN CAPITALS 
Clue: To get the name of its country, add 2 letters to the end of this world capital city
tunis

Category: RANKS & TITLES 
Clue: Owain Glyndwr, who died circa 1416, was the last native of his country to claim this title
prince of wales

Category: MUSEUMS 
Clue: Its museums include the Borgia Apartments, the Etruscan Museum & the Raphael Rooms

the vatican