In 1519, Tenochtitlán (now Mexico City) had running water, spotless streets thanks to a thousand-man sanitation crew, and a greater population than Paris. To the south, in what is now Bolivia, the people of the Beni landscaped a territory of 30,000 square miles, building 60-foot-high wooded islands over the flood plain, which was engineered with causeways, canals, reservoirs, and even fish farms. The Beni civilization thrived around the year 1000. Throughout the rise and fall of cultures in the Americas, of course, the guns, germs, and steel that would virtually obliterate their footprints were developing across the Atlantic. In 1491: New Revelations of the Americas Before Columbus, Charles C. Mann examines recent archaeological discoveries that may cause us to rewrite history. Far from the traditional picture of Indians (the term most indigenous peoples prefer) as naive hunter-gatherers waving ears of maize, greeting Christopher Columbus on the beach Timothy Treadwell–like, the civilizations in the Western Hemisphere were technologically sophisticated and well established. The invention of agriculture, which enables populations to settle and develop permanent institutions, occurred in Mesoamerica 10,000 years ago, a mere millennium or so after the rise of the first Sumerian civilization. Although Mann touches on early contacts with Europeans (imagine the first sight of short, overdressed, unwashed men with hair all over their faces arriving in ships), his aim is to show that the history of the Western Hemisphere is as complex and significant as that of the East. “Discover” the “new” world when Mann speaks at 7 p.m. Tuesday, Sept. 6, at Olsson’s Books and Records, 418 7th St. NW. Free. (202) 638-7610. (Janet Hopf)