Ancient Scandinavians dragged 59 boulders to a seaside cliff near what is now the Swedish fishing village of Kaseberga. They carefully arranged the massive stones - each weighing up to 1,800 kilograms - in the outline of a 67-meter-long ship overlooking the Baltic Sea.
     Archaeologists generally agree this megalithic structure, known as Ales Stenar ('Ale's Stones'), was assembled near the end of the Iron Age, as a burial monument. But a team of researchers now argues it's really 2,500 years old, dating from the Scandinavian Bronze Age, and was built as an astronomical calendar with the same underlying geometry as England's Stonehenge.
     Nils-Axel Moerner, a retired geologist from Stockholm University, co-authored the paper published in March in the International Journal of Astronomy and Astrophysics. Moerner says his team observed that the sun rises and sets at specific points around Ales Stenar at the summer and winter solstices. They also observed that certain aspects of the stone ship's geometry matched those of Stonehenge.
     Swedish archaeologist Martin Rundkvist, managing editor of the archaeology journal Fornvaennen, has another view. "The idea that the stone ship might have been an astronomical calendar has no supporters among academic archaeologists".
     The Swedish countryside is home to many similar megalithic structures, known as stone ships. Most of them date to Sweden's Late Iron Age (approximately 500-1000 CE), and serve as burial monuments, Rundkvist explains.
     Archaeologists using radiocarbon dating have calculated that Ales Stenar was built about 1,400 years ago - long after the date estimated by Moerner's team. "This was the world of Beowulf," says Rundkvist.

Edited from LiveScience (18 April 2012)