On Morocco’s northwest coast, near the entrance to the Strait of Gibraltar, Tangier is one of North Africa’s most alluring cities. Its history, of course, is long: the Phoenicians set up a trading post here as early as 12,000 years ago. In the late 1800s, it became a diplomatic hub for European powers jockeying for colonial influence. And by the 1950s, it was a haven for artists, novelists, diplomats and European royalty. In the latter half of the 20th century, however, the White City’s internat...