Andalucia was the first part of Spain to be conquered by the muslims from Africa, and the last part to be re-conquered by the Christians in the late 1400's. With all the armies marching back and forth, the regular folk soon learned to base themselves in some very unlikely but easily protected places, and Ronda is a good example. It sits atop a huge rocky outcrop, with a gorge dividing it into two parts. Houses line both sides, perched precariously alongside the gorge. Presumably there are no back doors to these places.