Trelew's star attraction is the paleontology museum, where four hushed and darkened galleries of fossils both real and replica take you back in time. You start among the South American megafauna (giant armadillos and the like) that may have cohabited with the first humans here, then plunge back to a time before the Andes existed. Back then Patagonia was a subtropical rain forest filled with dinosaurs, including one of the largest creatures ever to walk the earth: the 70-ton,
120-foot-long Argentinosaurus. Replicas of its massive leg bones are on display, along with countless other dino skeletons, including the latest discovery of the largest dinosaur in the world—a 130-foot-long herbivore. Other highlights include a 290-million-year-old spider fossil with a 3-foot leg span and the 70-million-year-old petrified eggs of a Carnotaurus. The visit ends with a peek into the workshop where paleontologists study and preserve newly unearthed fossils. Tours in English are available—they're a good idea, as only the introductions to each room are translated.