UKRAINE: Excavation and geophysical tests have allowed archaeologists to get a better sense of what may be one of the largest structures in prehistoric Europe, at the site of Nebelivka, but many mysteries remain. Belonging to the Trypillia culture, dating to 5300 to 2700 B.C., the site includes 1,500 structures, including massive assembly houses, one nearly an acre in size. Interestingly, the artifacts found in the large houses closely resemble what was found in typical households, as if the mega-structures were treated like houses with extra-large dimensions.—Samir S. Patel