IN 1939, George Orwell wrote of Westerners flocking to Marrakesh in search of “camels, castles, palm-trees, Foreign Legionnaires, brass trays and bandits.” Ever since, the city has been ravishing visitors with its teeming souks, ornate palaces and sybaritic night life. In recent years, a succession of high-end openings and restorations — most notably, the lavish reopening of the hotel La Mamounia — has transformed the city into an obligatory stop for jet-setters. Yet despite Marrakesh’s new cachet, the true treasures of the enigmatic city still hide down dusty side streets and behind sagging storefronts.