The Muslim rulers lost Granada and Alhambra in 1492 without the fortress itself being attacked when King Ferdinand II of Aragon and Queen Isabella of Castile took the surrounding region with an overwhelming force of numbers . The Muslim ruler Mustafar XII of Granada surrendered the Emirate of Granada in 1492 without the Alhambra itself being attacked when the forces of Los Reyes CatÃ licos , King Ferdinand II of Aragon and Queen Isabella I of Castile , took the surrounding territory with an overwhelming force of numbers .