On a trip to Córdoba and Granada a few years ago, I visited the ruins of Medina Azahara (Madinat al-Zahra), about 8 km to the west of Córdoba (there are trips organized by the tourist office). The Caliph of Córdoba had this palace town built in the 10th century, but it only lasted a few decades. Only a fraction is excavated, but it is a fascinating archaeological site to visit and walk around in, and there is a very interesting museum. It could have been inscribed as an extension of the Córdoba WHS, but considering its great archaeological potential, it’s just as well that it is a separate site. When I was there, there was talk of a problem with a kind of shantytown nearby that authorities thought would dissuade UNESCO from inscribing the site (although I didn't see any and there was certainly none in the immediate vicinity).