PAN, exterior, dusk. In 889 the Alcazaba was partially built by Savvar ben Hamdu. It was later extended on various occasions and in the 11th century the castle was converted into the most important fortress of Granada. 200 years later it was joined to the Nasrid palace. The Alcazaba boasts strong walls and robust towers. Alhambra was declared World Heritage Site by UNESCO in 1984.