'Avatar': Jet-Setting With the Cast

Before unveiling the 3-D sci-fi epic Avatar to an intensely curious audience at the December 10 world premiere, director James Cameron and actors Sam Worthington, Zoë Saldana, and Sigourney Weaver zipped around Paris, Berlin, Moscow, and London on a dizzying promotional tour. LIFE.com photographer Jeff Vespa was along for the ride, with exclusive access to those special, intimate moments that fans rarely see. In this gallery, get an inside peek at four head-spinning days in the lives of stars on the brink of a blockbuster. (Click through the gallery to see three other LIFE covers featuring the stars of Avatar — all four, plus highlights from this gallery, are available as special collectors' editions here.)