"I will go no further," William Niven s Indian guide declared. "Beyond on every ridge, as far as you can see is all a part of one great City of the Dead . . . the gods will permit no man to go further and from here I return." Niven, however, did continue on and discovered a remarkable expanse of ruins in the rugged state of Guerrero along Mexico s western coast. During the early 1890s, Niven s explorations were sponsored by the American Museum of Natural History. Later, he continued to explore on his own. His photographs, letters, diaries, and newspaper accounts are now the only source of...