An examination of the artistic and construction techniques, architecture and design of this immense fortress in the south of Spain, built mainly by the Nasrid dynasty in the 13th century. Its outward austerity conceals an explosion of refinement and ornamentation, gardens and marble fountains in the grandest tradition of Moorish style and Islamic art of the period.

In the heart of the Jordanian desert, the ancient city of Petra is full of mysteries. How was this architectural prowess achieved more than 2,000 years ago? © National Geographic