Ronda, the eastern end of the 'pueblos blancos' route of Andalucia, Spain, is a superbly situated prehistoric-Roman-Moorish-medieval city. The two halves of the city are perched on top of solid rock promontories separated by a a gorge so deep you can hardly see the river below. They are connected by the new bridge (puente nuevo) built in 1748 which supersedes the old bridge which in turn superseded the Roman bridge which is confusingly called the Arab Bridge. The old town on top of the cliff served residents as a fortification against invaders; despite or perhaps because of that, it changed hands frequently in ancient and medieval times.