Gibralfaro Fortress is located close to La Alcazaba which it is connected to by ducts from 2 of its towers.
Originally the place where the Gibralfaro lies is thought to have hosted a lighthouse build by the Phoenicians. On the remains of this lighthouse a fortress was build by Abderramán III and was later reconstructed as a castle by Yasuf I in the 14th century.
You can buy a combined ticket for La Alcazaba and Gibralfaro, but even though the sizes are connected it is not possible to walk from one to the other, and in fact a short bus journey is needed to get between them. The staff at the Alcazaba are very helpful, and will expain exactly where to get the bus from.
One of the highlights of the visit to the Gibralfaro is the incredible panoramic view of the town from the top.