Djémila

A Roman garrison town called Cuicul, founded in the first century AD on a narrow triangular plateau 900 metres up in the mountains of Numidia, and the reason it is a World Heritage Site is that the ground would not let the Romans build a Roman town. They laid out the forum and the two main streets anyway, cardo and decumanus, and then had to bend everything else to the ridge, which is how the theatre ended up outside the city walls, something Roman planners almost never did. By the fifth century there was a whole ecclesiastical quarter on top of it, three basilicas, a baptistery, a bath and a peristyle house. The modern name means beautiful. UNESCO listed it in 1982 specifically for the adaptation of Roman architecture to a mountain. Sétif Province, east of Algiers.