Ronald A. Messier

Like a sentinel standing guard long after his watch is over, the Bab Fez—the northern gate (shown here) of the once-grand medieval caravan city of Sijilmasa, Morocco—broods over a vista of decayed mud walls. A thousand years ago, sub-Saharan caravans laden with gold, ivory and slaves, as well as northern caravans bearing jewelry and textiles, entered through the Bab Fez and 11 other entryways in Sijilmasa’s circuit walls.