Unlike nearby Jericho, which collapsed (probably due to an earthquake rather than trumpets), ‘Ain Ghazal grew to become a metropolis. By 7000 B.C., the neolithic city (whose name is Arabic for “spring of the gazelles”) had more than 3,000 inhabitants and a more complex social structure than many anthropologists had, until recently, been willing to credit to a settlement so ancient. Gary O. Rollefson, who has been conducting excavations at the long-lost city for 15 years, discusses some of the Jordanian site’s secrets in a slide-illustrated Smithsonian Associates lecture, “Unraveling the Past: Neolithic ‘Ain Ghazal.” At 8 p.m. at the Navy Memorial, 701 Pennsylvania Ave. NW. $13. For reservations call (202) 357-3030. (MJ)