Egypt: Alexandria Qaitbay Citadel

This citadel was built on the very spot where the Lighthouse of Alexandria, one of the seven wonders of the world, used to be. It fell out of use, was damaged in the earthquake some time in the middle ages (14th century), and by the time the sultan Qaitbay got to it, there were nothing but ruins. Supposedly, the citadel is built using the stones of that wonder. So who knows...