As the world becomes increasingly urbanized, the number of megacities is growing rapidly. Today there are 37 cities worldwide with populations of greater than 10 million, and 84 with populations…

Philip E. Karp, Peter Ellis, Barjor Mehta |

In Mali, residents of Timbuktu take part in the maintenance of the Djingareyber Mosque, a World Heritage Site, applying traditional repair techniques. (Tiecoura Ndaou / UN Photo) Imagine a city…

Sameh Wahba, Barbara Minguez Garcia |