National Geographic December 1991

Pittsburgh- -Stronger Than Steel
Former king of steel, Pittsburgh paints on a bright new face with riverside parks, high- tech laboratories, and gleaming corporate headquarters, yet vibrant old neighborhoods endure.
Ibn Battuta, Prince of Travelers
In an epic adventure that lasted three decades, a 14th- century Muslim scholar roamed 75, 000 miles through Africa and Asia – – one of the world’s great journeys of exploration.
Return to Pearl Harbor { Pearl Harbor: A Return to the Day of Infamy}
Fifty years after the surprise attack that drew the United States into World War II, American and Japanese survivors share recollections of that fateful day. A map supplement details key events in the global conflict.
Australia’s Magnificent Pearls
Farming oysters in the nutrient- rich tides off their northwest coast, Australians produce lustrous South Sea treasures – – the world’s largest cultured pearls.
High Frontier of the Rain Forest Canopy { Rain Forest Canopy: The High Frontier}
Penetrating a little- known realm more than a hundred feet up in the trees, scientists are unlocking secrets of plants and animals that never touch ground.